Gap enhancement for flexible symbols

ABSTRACT

An integrated access and backhaul (IAB) apparatus transmits a set of values to a child IAB node corresponding to a transition type for the child IAB node, determines that the child IAB node will perform a transition at a transition time with a symbol adjacent to the transmission time having a flexible resource type, and provides a number of guard symbols at the transition time based on determining that the symbol has the flexible resource type.

CROSS REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit of U.S. Provisional Application Ser. No. 62/958,167, entitled “GAP ENHANCEMENT FOR FLEXIBLE SYMBOLS” and filed on Jan. 7, 2020, which is expressly incorporated by reference herein in its entirety.

BACKGROUND Technical Field

The present disclosure relates generally to communication systems, and more particularly, to integrated access and backhaul networks

Introduction

Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources. Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.

These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example telecommunication standard is 5G New Radio (NR). 5G NR is part of a continuous mobile broadband evolution promulgated by Third Generation Partnership Project (3GPP) to meet new requirements associated with latency, reliability, security, scalability (e.g., with Internet of Things (IoT)), and other requirements. 5G NR includes services associated with enhanced mobile broadband (eMBB), massive machine type communications (mMTC), and ultra reliable low latency communications (URLLC). Some aspects of 5G NR may be based on the 4G Long Term Evolution (LTE) standard. There exists a need for further improvements in 5G NR technology. These improvements may also be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.

SUMMARY

The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.

In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus transmits a set of values to a child IAB node, each value of the set of values corresponding to a transition type for a transition of the child IAB node between use of a mobile terminal of the child IAB node and use of a distributed unit of the child IAB node, a transition type corresponding to a first resource type for resources immediately before a transition time and to a second resource type for resources immediately after the transition time, determines that the child IAB node will perform a transition at a transition time, wherein a symbol immediately before the transition or immediately after the transition has a resource type of flexible, and provides a number of guard symbols at the transition time, the number of guard symbols being based on determining that the symbol immediately before the transition or immediately after the transition has the resource type of flexible.

In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus receives a set of values from a parent IAB apparatus, each value of the set of values corresponding to a transition type for a transition of the IAB node between use of a mobile terminal of the IAB node and use of a distributed unit of the IAB node, a transition type corresponding to a first resource type for resources immediately before a transition time and to a second resource type for resources immediately after the transition time, determines to perform a transition at a transition time, wherein a symbol immediately before the transition or immediately after the transition has a resource type of flexible, and receives a number of guard symbols at the transition time, the number of guard symbols being based on determining that the symbol immediately before the transition or immediately after the transition has the resource type of flexible.

In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus transmits a set of values to a parent IAB apparatus, each value of the set of values corresponding to a transition type for a transition of the IAB node between use of a mobile terminal of the IAB node and use of a distributed unit of the IAB node, a transition type corresponding to a first resource type for resources immediately before a transition time and to a second resource type for resources immediately after the transition time, determines to perform a transition at a transition time, wherein a symbol immediately before the transition or immediately after the transition has a resource type of flexible, and receives a number of guard symbols from the parent IAB apparatus at the transition time, the number of guard symbols being based on determining that the symbol immediately before the transition or immediately after the transition has the resource type of flexible.

In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus receives a set of values from a child IAB node, each value of the set of values corresponding to a transition type for a transition of the child IAB node between use of a mobile terminal of the child IAB node and use of a distributed unit of the child IAB node, a transition type corresponding to a first resource type for resources immediately before a transition time and to a second resource type for resources immediately after the transition time, determines that the child IAB node will perform a transition at a transition time, wherein a symbol immediately before the transition or immediately after the transition has a resource type of flexible, and provides a number of guard symbols at the transition time, the number of guard symbols being based on determining that the symbol immediately before the transition or immediately after the transition has the resource type of flexible.

To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of various aspects may be employed, and this description is intended to include all such aspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of a wireless communications system and an access network.

FIGS. 2A, 2B, 2C, and 2D are diagrams illustrating examples of a first 5G/NR frame, DL channels within a 5G/NR subframe, a second 5G/NR frame, and UL channels within a 5G/NR subframe, respectively.

FIG. 3 is a diagram illustrating an example of a base station and user equipment (UE) in an access network.

FIG. 4 is a diagram illustrating an integrated access and backhaul (IAB) network.

FIG. 5 is a diagram illustrating an IAB network and components thereof.

FIG. 6 is a diagram illustrating examples of interaction between an IAB donor, an IAB node, and a child IAB node.

FIG. 7 is a diagram illustrating communication between a child IAB node and its parent.

FIG. 8 is a table illustrating IAB node transition types.

FIG. 9 is a communication diagram illustrating guard symbol signaling between a child IAB node and a parent IAB apparatus.

FIG. 10A is a diagram illustrating guard symbols at a transition from DU to MT.

FIG. 10B is a diagram illustrating guard symbols at a transition from MT to DU.

FIG. 11 is a table illustrating IAB node transition types with flexible DU resources.

FIG. 12 is a table illustrating IAB node transition types with flexible MT resources.

FIG. 13 is a table illustrating IAB node transition types with flexible MT resources and flexible DU resources.

FIG. 14 is a flowchart of a method of wireless communication.

FIG. 15 is a flowchart of a method of wireless communication.

FIG. 16 is a flowchart of a method of wireless communication.

FIG. 17 is a flowchart of a method of wireless communication.

FIG. 18 is a diagram illustrating an example of a hardware implementation for an apparatus.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

Several aspects of telecommunication systems will now be presented with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, components, circuits, processes, algorithms, etc. (collectively referred to as “elements”). These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

By way of example, an element, or any portion of an element, or any combination of elements may be implemented as a “processing system” that includes one or more processors. Examples of processors include microprocessors, microcontrollers, graphics processing units (GPUs), central processing units (CPUs), application processors, digital signal processors (DSPs), reduced instruction set computing (RISC) processors, systems on a chip (SoC), baseband processors, field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. One or more processors in the processing system may execute software. Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software components, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

Accordingly, in one or more example embodiments, the functions described may be implemented in hardware, software, or any combination thereof. If implemented in software, the functions may be stored on or encoded as one or more instructions or code on a computer-readable medium. Computer-readable media includes computer storage media. Storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise a random-access memory (RAM), a read-only memory (ROM), an electrically erasable programmable ROM (EEPROM), optical disk storage, magnetic disk storage, other magnetic storage devices, combinations of the aforementioned types of computer-readable media, or any other medium that can be used to store computer executable code in the form of instructions or data structures that can be accessed by a computer.

FIG. 1 is a diagram illustrating an example of a wireless communications system and an access network 100. The wireless communications system (also referred to as a wireless wide area network (WWAN)) includes base stations 102, UEs 104, an Evolved Packet Core (EPC) 160, and another core network 190 (e.g., a 5G Core (5GC)). The base stations 102 may include macrocells (high power cellular base station) and/or small cells (low power cellular base station). The macrocells include base stations. The small cells include femtocells, picocells, and microcells.

The base stations 102 configured for 4G LTE (collectively referred to as Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) may interface with the EPC 160 through first backhaul links 132 (e.g., S1 interface). The base stations 102 configured for 5G NR (collectively referred to as Next Generation RAN (NG-RAN)) may interface with core network 190 through second backhaul links 184. In addition to other functions, the base stations 102 may perform one or more of the following functions: transfer of user data, radio channel ciphering and deciphering, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection setup and release, load balancing, distribution for non-access stratum (NAS) messages, NAS node selection, synchronization, radio access network (RAN) sharing, multimedia broadcast multicast service (MBMS), subscriber and equipment trace, RAN information management (RIM), paging, positioning, and delivery of warning messages. The base stations 102 may communicate directly or indirectly (e.g., through the EPC 160 or core network 190) with each other over third backhaul links 134 (e.g., X2 interface). The third backhaul links 134 may be wired or wireless.

The base stations 102 may wirelessly communicate with the UEs 104. Each of the base stations 102 may provide communication coverage for a respective geographic coverage area 110. There may be overlapping geographic coverage areas 110. For example, the small cell 102′ may have a coverage area 110′ that overlaps the coverage area 110 of one or more macro base stations 102. A network that includes both small cell and macrocells may be known as a heterogeneous network. A heterogeneous network may also include Home Evolved Node Bs (eNBs) (HeNBs), which may provide service to a restricted group known as a closed subscriber group (CSG). The communication links 120 between the base stations 102 and the UEs 104 may include uplink (UL) (also referred to as reverse link) transmissions from a UE 104 to a base station 102 and/or downlink (DL) (also referred to as forward link) transmissions from a base station 102 to a UE 104. The communication links 120 may use multiple-input and multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and/or transmit diversity. The communication links may be through one or more carriers. The base stations 102/UEs 104 may use spectrum up to Y MHz (e.g., 5, 10, 15, 20, 100, 400, etc. MHz) bandwidth per carrier allocated in a carrier aggregation of up to a total of Yx MHz (x component carriers) used for transmission in each direction. The carriers may or may not be adjacent to each other. Allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated for DL than for UL). The component carriers may include a primary component carrier and one or more secondary component carriers. A primary component carrier may be referred to as a primary cell (PCell) and a secondary component carrier may be referred to as a secondary cell (SCell).

Certain UEs 104 may communicate with each other using device-to-device (D2D) communication link 158. The D2D communication link 158 may use the DL/UL WWAN spectrum. The D2D communication link 158 may use one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH), a physical sidelink discovery channel (PSDCH), a physical sidelink shared channel (PSSCH), and a physical sidelink control channel (PSCCH). D2D communication may be through a variety of wireless D2D communications systems, such as for example, FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on the IEEE 802.11 standard, LTE, or NR.

The wireless communications system may further include a Wi-Fi access point (AP) 150 in communication with Wi-Fi stations (STAs) 152 via communication links 154 in a 5 GHz unlicensed frequency spectrum. When communicating in an unlicensed frequency spectrum, the STAs 152/AP 150 may perform a clear channel assessment (CCA) prior to communicating in order to determine whether the channel is available.

The small cell 102′ may operate in a licensed and/or an unlicensed frequency spectrum. When operating in an unlicensed frequency spectrum, the small cell 102′ may employ NR and use the same 5 GHz unlicensed frequency spectrum as used by the Wi-Fi AP 150. The small cell 102′, employing NR in an unlicensed frequency spectrum, may boost coverage to and/or increase capacity of the access network.

A base station 102, whether a small cell 102′ or a large cell (e.g., macro base station), may include and/or be referred to as an eNB, gNodeB (gNB), or another type of base station. Some base stations, such as gNB 180 may operate in a traditional sub 6 GHz spectrum, in millimeter wave (mmW) frequencies, and/or near mmW frequencies in communication with the UE 104. When the gNB 180 operates in mmW or near mmW frequencies, the gNB 180 may be referred to as an mmW base station. Extremely high frequency (EHF) is part of the RF in the electromagnetic spectrum. EHF has a range of 30 GHz to 300 GHz and a wavelength between 1 millimeter and 10 millimeters. Radio waves in the band may be referred to as a millimeter wave. Near mmW may extend down to a frequency of 3 GHz with a wavelength of 100 millimeters. The super high frequency (SHF) band extends between 3 GHz and 30 GHz, also referred to as centimeter wave. Communications using the mmW/near mmW radio frequency band (e.g., 3 GHz-300 GHz) has extremely high path loss and a short range. The mmW base station 180 may utilize beamforming 182 with the UE 104 to compensate for the extremely high path loss and short range. The base station 180 and the UE 104 may each include a plurality of antennas, such as antenna elements, antenna panels, and/or antenna arrays to facilitate the beamforming.

The base station 180 may transmit a beamformed signal to the UE 104 in one or more transmit directions 182′. The UE 104 may receive the beamformed signal from the base station 180 in one or more receive directions 182″. The UE 104 may also transmit a beamformed signal to the base station 180 in one or more transmit directions. The base station 180 may receive the beamformed signal from the UE 104 in one or more receive directions. The base station 180/UE 104 may perform beam training to determine the best receive and transmit directions for each of the base station 180/UE 104. The transmit and receive directions for the base station 180 may or may not be the same. The transmit and receive directions for the UE 104 may or may not be the same.

The EPC 160 may include a Mobility Management Entity (MME) 162, other MMES 164, a Serving Gateway 166, a Multimedia Broadcast Multicast Service (MBMS) Gateway 168, a Broadcast Multicast Service Center (BM-SC) 170, and a Packet Data Network (PDN) Gateway 172. The MME 162 may be in communication with a Home Subscriber Server (HSS) 174. The MME 162 is the control node that processes the signaling between the UEs 104 and the EPC 160. Generally, the MME 162 provides bearer and connection management. All user Internet protocol (IP) packets are transferred through the Serving Gateway 166, which itself is connected to the PDN Gateway 172. The PDN Gateway 172 provides UE IP address allocation as well as other functions. The PDN Gateway 172 and the BM-SC 170 are connected to the IP Services 176. The IP Services 176 may include the Internet, an intranet, an IP Multimedia Subsystem (IMS), a PS Streaming Service, and/or other IP services. The BM-SC 170 may provide functions for MBMS user service provisioning and delivery. The BM-SC 170 may serve as an entry point for content provider MBMS transmission, may be used to authorize and initiate MBMS Bearer Services within a public land mobile network (PLMN), and may be used to schedule MBMS transmissions. The MBMS Gateway 168 may be used to distribute MBMS traffic to the base stations 102 belonging to a Multicast Broadcast Single Frequency Network (MBSFN) area broadcasting a particular service, and may be responsible for session management (start/stop) and for collecting eMBMS related charging information.

The core network 190 may include a Access and Mobility Management Function (AMF) 192, other AMFs 193, a Session Management Function (SMF) 194, and a User Plane Function (UPF) 195. The AMF 192 may be in communication with a Unified Data Management (UDM) 196. The AMF 192 is the control node that processes the signaling between the UEs 104 and the core network 190. Generally, the AMF 192 provides QoS flow and session management. All user Internet protocol (IP) packets are transferred through the UPF 195. The UPF 195 provides UE IP address allocation as well as other functions. The UPF 195 is connected to the IP Services 197. The IP Services 197 may include the Internet, an intranet, an IP Multimedia Subsystem (IMS), a PS Streaming Service, and/or other IP services.

The base station may include and/or be referred to as a gNB, Node B, eNB, an access point, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), a transmit reception point (TRP), or some other suitable terminology. The base station 102 provides an access point to the EPC 160 or core network 190 for a UE 104. Examples of UEs 104 include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a personal digital assistant (PDA), a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., MP3 player), a camera, a game console, a tablet, a smart device, a wearable device, a vehicle, an electric meter, a gas pump, a large or small kitchen appliance, a healthcare device, an implant, a sensor/actuator, a display, or any other similar functioning device. Some of the UEs 104 may be referred to as IoT devices (e.g., parking meter, gas pump, toaster, vehicles, heart monitor, etc.). The UE 104 may also be referred to as a station, a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology.

Referring again to FIG. 1 , in certain aspects, the base station 180 may include a flexible guard symbol provision component 198. The base station 180 may be a part of an integrated access and backhaul (IAB) network (e.g., may be or may include an IAB node or an IAB donor), and the flexible guard symbol provision component 198 may determine how many guard symbols to be provided by different nodes of the IAB network when a node of the network transitions between its mobile termination or mobile terminal (MT) and its distributed unit (DU), but has flexible resources allocated adjacent to the transition time. Although the following description may be focused on 5G NR, the concepts described herein may be applicable to other similar areas, such as LTE, LTE-A, CDMA, GSM, and other wireless technologies.

FIG. 2A is a diagram 200 illustrating an example of a first subframe within a 5G/NR frame structure. FIG. 2B is a diagram 230 illustrating an example of DL channels within a 5G/NR subframe. FIG. 2C is a diagram 250 illustrating an example of a second subframe within a 5G/NR frame structure. FIG. 2D is a diagram 280 illustrating an example of UL channels within a 5G/NR subframe. The 5G/NR frame structure may be FDD in which for a particular set of subcarriers (carrier system bandwidth), subframes within the set of subcarriers are dedicated for either DL or UL, or may be TDD in which for a particular set of subcarriers (carrier system bandwidth), subframes within the set of subcarriers are dedicated for both DL and UL. In the examples provided by FIGS. 2A, 2C, the 5G/NR frame structure is assumed to be TDD, with subframe 4 being configured with slot format 28 (with mostly DL), where D is DL, U is UL, and X is flexible for use between DL/UL, and subframe 3 being configured with slot format 34 (with mostly UL). While subframes 3, 4 are shown with slot formats 34, 28, respectively, any particular subframe may be configured with any of the various available slot formats 0-61. Slot formats 0, 1 are all DL, UL, respectively. Other slot formats 2-61 include a mix of DL, UL, and flexible symbols. UEs are configured with the slot format (dynamically through DL control information (DCI), or semi-statically/statically through radio resource control (RRC) signaling) through a received slot format indicator (SFI). Note that the description infra applies also to a 5G/NR frame structure that is TDD.

Other wireless communication technologies may have a different frame structure and/or different channels. A frame (10 ms) may be divided into 10 equally sized subframes (1 ms). Each subframe may include one or more time slots. Subframes may also include mini-slots, which may include 7, 4, or 2 symbols. Each slot may include 7 or 14 symbols, depending on the slot configuration. For slot configuration 0, each slot may include 14 symbols, and for slot configuration 1, each slot may include 7 symbols. The symbols on DL may be cyclic prefix (CP) OFDM (CP-OFDM) symbols. The symbols on UL may be CP-OFDM symbols (for high throughput scenarios) or discrete Fourier transform (DFT) spread OFDM (DFT-s-OFDM) symbols (also referred to as single carrier frequency-division multiple access (SC-FDMA) symbols) (for power limited scenarios; limited to a single stream transmission). The number of slots within a subframe is based on the slot configuration and the numerology. For slot configuration 0, different numerologies μ 0 to 5 allow for 1, 2, 4, 8, 16, and 32 slots, respectively, per subframe. For slot configuration 1, different numerologies 0 to 2 allow for 2, 4, and 8 slots, respectively, per subframe. Accordingly, for slot configuration 0 and numerology μ, there are 14 symbols/slot and 2μ slots/subframe. The subcarrier spacing and symbol length/duration are a function of the numerology. The subcarrier spacing may be equal to 2μ*15 kHz, where μ is the numerology 0 to 5. As such, the numerology μ=0 has a subcarrier spacing of 15 kHz and the numerology μ=5 has a subcarrier spacing of 480 kHz. The symbol length/duration is inversely related to the subcarrier spacing. FIGS. 2A-2D provide an example of slot configuration 0 with 14 symbols per slot and numerology μ=2 with 4 slots per subframe. The slot duration is 0.25 ms, the subcarrier spacing is 60 kHz, and the symbol duration is approximately 16.67 μs.

A resource grid may be used to represent the frame structure. Each time slot includes a resource block (RB) (also referred to as physical RBs (PRBs)) that extends 12 consecutive subcarriers. The resource grid is divided into multiple resource elements (REs). The number of bits carried by each RE depends on the modulation scheme.

As illustrated in FIG. 2A, some of the REs carry reference (pilot) signals (RS) for the UE. The RS may include demodulation RS (DM-RS) (indicated as R_(x) for one particular configuration, where 100x is the port number, but other DM-RS configurations are possible) and channel state information reference signals (CSI-RS) for channel estimation at the UE. The RS may also include beam measurement RS (BRS), beam refinement RS (BRRS), and phase tracking RS (PT-RS).

FIG. 2B illustrates an example of various DL channels within a subframe of a frame. The physical downlink control channel (PDCCH) carries DCI within one or more control channel elements (CCEs), each CCE including nine RE groups (REGs), each REG including four consecutive REs in an OFDM symbol. A primary synchronization signal (PSS) may be within symbol 2 of particular subframes of a frame. The PSS is used by a UE 104 to determine subframe/symbol timing and a physical layer identity. A secondary synchronization signal (SSS) may be within symbol 4 of particular subframes of a frame. The SSS is used by a UE to determine a physical layer cell identity group number and radio frame timing. Based on the physical layer identity and the physical layer cell identity group number, the UE can determine a physical cell identifier (PCI). Based on the PCI, the UE can determine the locations of the aforementioned DM-RS. The physical broadcast channel (PBCH), which carries a master information block (MIB), may be logically grouped with the PSS and SSS to form a synchronization signal (SS)/PBCH block. The MIB provides a number of RBs in the system bandwidth and a system frame number (SFN). The physical downlink shared channel (PDSCH) carries user data, broadcast system information not transmitted through the PBCH such as system information blocks (SIBs), and paging messages.

As illustrated in FIG. 2C, some of the REs carry DM-RS (indicated as R for one particular configuration, but other DM-RS configurations are possible) for channel estimation at the base station. The UE may transmit DM-RS for the physical uplink control channel (PUCCH) and DM-RS for the physical uplink shared channel (PUSCH). The PUSCH DM-RS may be transmitted in the first one or two symbols of the PUSCH. The PUCCH DM-RS may be transmitted in different configurations depending on whether short or long PUCCHs are transmitted and depending on the particular PUCCH format used. The UE may transmit sounding reference signals (SRS). The SRS may be transmitted in the last symbol of a subframe. The SRS may have a comb structure, and a UE may transmit SRS on one of the combs. The SRS may be used by a base station for channel quality estimation to enable frequency-dependent scheduling on the UL.

FIG. 2D illustrates an example of various UL channels within a subframe of a frame. The PUCCH may be located as indicated in one configuration. The PUCCH carries uplink control information (UCI), such as scheduling requests, a channel quality indicator (CQI), a precoding matrix indicator (PMI), a rank indicator (RI), and HARQ ACK/NACK feedback. The PUSCH carries data, and may additionally be used to carry a buffer status report (BSR), a power headroom report (PHR), and/or UCI.

FIG. 3 is a block diagram of a base station 310 in communication with a UE 350 in an access network. In some aspects, the base station 310 may be an IAB apparatus such as an IAB node or an IAB donor, or may include an IAB apparatus. In the DL, IP packets from the EPC 160 may be provided to a controller/processor 375. The controller/processor 375 implements layer 3 and layer 2 functionality. Layer 3 includes a radio resource control (RRC) layer, and layer 2 includes a service data adaptation protocol (SDAP) layer, a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, and a medium access control (MAC) layer. The controller/processor 375 provides RRC layer functionality associated with broadcasting of system information (e.g., MIB, SIBs), RRC connection control (e.g., RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release), inter radio access technology (RAT) mobility, and measurement configuration for UE measurement reporting; PDCP layer functionality associated with header compression/decompression, security (ciphering, deciphering, integrity protection, integrity verification), and handover support functions; RLC layer functionality associated with the transfer of upper layer packet data units (PDUs), error correction through ARQ, concatenation, segmentation, and reassembly of RLC service data units (SDUs), re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto transport blocks (TBs), demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

The transmit (TX) processor 316 and the receive (RX) processor 370 implement layer 1 functionality associated with various signal processing functions. Layer 1, which includes a physical (PHY) layer, may include error detection on the transport channels, forward error correction (FEC) coding/decoding of the transport channels, interleaving, rate matching, mapping onto physical channels, modulation/demodulation of physical channels, and MIMO antenna processing. The TX processor 316 handles mapping to signal constellations based on various modulation schemes (e.g., binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), M-phase-shift keying (M-PSK), M-quadrature amplitude modulation (M-QAM)). The coded and modulated symbols may then be split into parallel streams. Each stream may then be mapped to an OFDM subcarrier, multiplexed with a reference signal (e.g., pilot) in the time and/or frequency domain, and then combined together using an Inverse Fast Fourier Transform (IFFT) to produce a physical channel carrying a time domain OFDM symbol stream. The OFDM stream is spatially precoded to produce multiple spatial streams. Channel estimates from a channel estimator 374 may be used to determine the coding and modulation scheme, as well as for spatial processing. The channel estimate may be derived from a reference signal and/or channel condition feedback transmitted by the UE 350. Each spatial stream may then be provided to a different antenna 320 via a separate transmitter 318TX. Each transmitter 318TX may modulate an RF carrier with a respective spatial stream for transmission.

At the UE 350, each receiver 354RX receives a signal through its respective antenna 352. Each receiver 354RX recovers information modulated onto an RF carrier and provides the information to the receive (RX) processor 356. The TX processor 368 and the RX processor 356 implement layer 1 functionality associated with various signal processing functions. The RX processor 356 may perform spatial processing on the information to recover any spatial streams destined for the UE 350. If multiple spatial streams are destined for the UE 350, they may be combined by the RX processor 356 into a single OFDM symbol stream. The RX processor 356 then converts the OFDM symbol stream from the time-domain to the frequency domain using a Fast Fourier Transform (FFT). The frequency domain signal comprises a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier, and the reference signal, are recovered and demodulated by determining the most likely signal constellation points transmitted by the base station 310. These soft decisions may be based on channel estimates computed by the channel estimator 358. The soft decisions are then decoded and deinterleaved to recover the data and control signals that were originally transmitted by the base station 310 on the physical channel. The data and control signals are then provided to the controller/processor 359, which implements layer 3 and layer 2 functionality.

The controller/processor 359 can be associated with a memory 360 that stores program codes and data. The memory 360 may be referred to as a computer-readable medium. In the UL, the controller/processor 359 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, and control signal processing to recover IP packets from the EPC 160. The controller/processor 359 is also responsible for error detection using an ACK and/or NACK protocol to support HARQ operations.

Similar to the functionality described in connection with the DL transmission by the base station 310, the controller/processor 359 provides RRC layer functionality associated with system information (e.g., MIB, SIBs) acquisition, RRC connections, and measurement reporting; PDCP layer functionality associated with header compression/decompression, and security (ciphering, deciphering, integrity protection, integrity verification); RLC layer functionality associated with the transfer of upper layer PDUs, error correction through ARQ, concatenation, segmentation, and reassembly of RLC SDUs, re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

Channel estimates derived by a channel estimator 358 from a reference signal or feedback transmitted by the base station 310 may be used by the TX processor 368 to select the appropriate coding and modulation schemes, and to facilitate spatial processing. The spatial streams generated by the TX processor 368 may be provided to different antenna 352 via separate transmitters 354TX. Each transmitter 354TX may modulate an RF carrier with a respective spatial stream for transmission.

The UL transmission is processed at the base station 310 in a manner similar to that described in connection with the receiver function at the UE 350. Each receiver 318RX receives a signal through its respective antenna 320. Each receiver 318RX recovers information modulated onto an RF carrier and provides the information to a RX processor 370.

The controller/processor 375 can be associated with a memory 376 that stores program codes and data. The memory 376 may be referred to as a computer-readable medium. In the UL, the controller/processor 375 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, control signal processing to recover IP packets from the UE 350. IP packets from the controller/processor 375 may be provided to the EPC 160. The controller/processor 375 is also responsible for error detection using an ACK and/or NACK protocol to support HARQ operations.

At least one of the TX processor 316, the RX processor 370, and the controller/processor 375 may be configured to perform aspects in connection with 198 of FIG. 1 .

FIG. 4 is a diagram illustrating an integrated access and backhaul (IAB) network 400. The IAB network 400 may include an anchor node (that may be referred to herein as an “IAB donor”) 410 and access nodes (that may be referred to herein as “IAB nodes”) 420. The IAB donor 410 may be a base station, such as a gNB or eNB, and may perform functions to control the IAB network 400. The IAB nodes 420 may comprise L2 relay nodes, etc. Together, the IAB donor 410 and the IAB nodes 420 share resources to provide an access network and a backhaul network to core network 490. For example, resources may be shared between access links and backhaul links in the IAB network.

UEs 430 interface with the IAB nodes 420 or the IAB donor 410 through access links 470. The IAB nodes 420 communicate with each other and with the IAB donor 410 through backhaul links 460. The IAB donor 410 is connected to the core network 490 via a wireline backhaul link 450. UEs 430 communicate with the core network by relaying messages through their respective access link 470 to the IAB network 400, which then may relay the message through backhaul links 460 to the IAB donor 410 to communicate to the core network through the wireline backhaul link 450. Similarly, the core network may communicate with a UE 430 by sending a message to the IAB donor 410 through the wireline backhaul link 450. The IAB donor 410 sends the message through the IAB network 400 via backhaul links 460 to the IAB node 420 connected to the UE 430, and the IAB node 420 sends the message to the UE 430 via the access link 470.

FIG. 5 is a diagram illustrating an IAB network 500 and components thereof. The IAB network 500 includes an IAB donor 510 and IAB nodes 520. The IAB nodes, as well as the IAB donor, may provide wireless access links to UEs 530.

The IAB donor 510 may be considered a root node of the tree structure of the IAB network 500. The IAB donor node 510 may be connected to the core network 590 via a wired connection 591. The wired connection may comprise, e.g., a wireline fiber. The IAB donor node 510 may provide a connection to one or more IAB nodes 520 a. The IAB nodes 520 a may each be referred to as a child node of the IAB donor node 510. The IAB donor node 510 may also provide a connection to one or more UE 530 a, which may be referred to as a child UE of IAB donor 510. The IAB donor 510 may be connected to its child IAB nodes 520 a via backhaul links 560, and may be connected to the child UEs 530 a via access links 570. The IAB nodes 520 a that are children nodes of IAB node 510 may also have IAB node(s) 520 b and/or UE(s) 530 b as children. For example, IAB nodes 520 b may further connect to child nodes and/or child UEs. FIG. 5 illustrates IAB nodes 520 b providing an access link to UEs 530 c, respectively.

The IAB donor 510 may include a central unit (CU) and a distributed unit (DU). The central unit CU may provide control for the IAB nodes 520 a, 520 b in the IAB network 500. For example, the CU may be responsible for configuration of the IAB network 500. The CU may perform RRC/PDCP layer functions. The DU may perform scheduling. For example, the DU may schedule resources for communication by the child IAB nodes 520 a and/or UEs 530 a of the IAB donor 510.

The IAB nodes 520 a, 520 b may include a mobile termination or mobile terminal (MT) and a DU. The MT of IAB node 520 a may operate as a scheduled node, scheduled similar to a UE 530 a by the DU of the parent node, e.g., IAB donor 510. The MT of IAB node 520 b may operate as a scheduled node of parent node 520 a. The DU may schedule the child IAB nodes 520 b and UEs 530 b of the IAB node 520 a. As an IAB node may provide a connection to an IAB node that in turn provides a connection for another IAB node, the pattern of a parent IAB node comprising a DU that schedules a child IAB node/child UE may continue.

FIG. 6 is a diagram 600 illustrating examples of interaction between an IAB donor 610, an IAB node 620, and a child IAB node 630. The CU 612 of the IAB donor 610 may provide centralized management of the resources available for communication of the IAB nodes. The CU 612 of the IAB donor 610 may allocate the resources semi-statically. Additionally or alternatively, the soft resources of a child node may be controlled in a distributed dynamic fashion by the parent of the child node (e.g., the DU 624 or 614 of the parent node). For example, the DU 624 of the IAB node 620 may allocate the soft resources of the child IAB node 630 through dynamic control signaling.

The MTs 622 and 632 may have resources that are downlink (DL) resources, uplink (UL) resources, or flexible (F) resources. The DUs 614, 624, and 634 may have hard DL resources, hard UL resources, and/or hard F resources. The DUs 614, 624, and 634 may have soft DL resources, soft UL resources, and/or soft flexible resources. In addition to hard or soft resources types, the DUs 614, 624, and 634 may have resources that are not available (NA) type resources.

The CU 612 of the IAB donor 610 may communicate with the DU 624 of the IAB node 620 and the DU 634 of the child IAB node 630 over an F1 interface 640. The F1 interface 640 may support exchanging information with or transferring encapsulated RRC messages to a child IAB node (e.g., the MT of a child of the receiving IAB node) (e.g., transferring an encapsulated RRC message for the child IAB node 630 to the DU 624 of the IAB node 620). In some aspects, the CU 612 may configure the resource pattern of the DU 624 of the IAB node 620 over the F1 interface 640.

The DU 624 of the IAB node 620 may communicate with the MT 632 of the child IAB node 630 over a Uu air interface 650. The Uu air interface 650 may support transferring RRC messages received from the CU 612 of the IAB donor 610 to the MT 632 of the child IAB node 630, and may support the DU 624 of the IAB node 620 dynamically scheduling the MT 632 of the child IAB node 630. In some aspects, the IAB node 620 may dynamically control the soft resources of the DU 634 of the child IAB node 630 over the Uu air interface 650.

FIG. 7 is a diagram 700 illustrating communication between a child IAB node and its parent. The child IAB node may be in TDD mode.

An IAB apparatus may utilize its MT to communicate with its parent IAB apparatus (e.g., the DU of the parent IAB node or IAB donor), and may utilize its DU to communicate with its children (e.g., child IAB nodes or UEs). Resources of a DU may be configured as UL, DL, or flexible (F). The DU may transmit downlink information to a grandchild IAB apparatus (e.g., the MT of a child IAB node or a UE) on resources configured as DL. The DU may receive uplink information from the grandchild IAB apparatus on resources configured as UL. The MT may determine whether resources configured as F will be used as DL or UL at a later time, for example based on receiving an indication (e.g, from the parent IAB apparatus or the IAB donor for the IAB network) whether resources configured as F should be used as DL or UL.

Resources of a DU may additionally be configured as hard, soft, or not available (NA), to avoid conflict with resources being utilized by the MT. When a resource is indicated as hard, the DU can assume it can use the resource regardless of the MT's configuration. The DU may determine whether to use the hard resource to communicate with the child IAB apparatus regardless of whether MT has an allocation from the parent IAB apparatus. In some aspects, the DU may decide to ignore the MT's allocation from the parent IAB apparatus and use the hard resource to communicate with its child node. In some aspects, the DU may decide to give priority to the MT to communicate with the parent IAB apparatus and not to use the hard resource to communicate with the grandchild IAB node. When a resource is indicated as NA, it is unavailable for use by the DU. When a resource is indicated as soft, the DU may determine whether it may utilize the resource based on whether doing so would impact the MT transmitting or receiving on the resource. A soft resource may be explicitly or implicitly indicated as available. A soft resource is explicitly indicated as available when a parent IAB apparatus indicates to the child IAB node that the resource will be available (e.g., the parent has not scheduled the MT of the child IAB node to transmit on the soft resource). A soft resource is implicitly indicated as available when the child IAB node determines that it's DU can utilize the soft resources without interfering with transmitting or receiving by the child IAB node's MT (e.g., without indication from the parent IAB apparatus).

The diagram 700 of FIG. 7 illustrates a parent IAB apparatus communicating with a child IAB node on a first set of time domain resources 710, a second set of time domain resources 720, and a third set of time domain resources 730. Specifically, the diagram 700 illustrates the configuration of the DU of the parent IAB apparatus (“Parent DU”), the configuration of the MT of the child IAB node (“Child MT”), and the configuration of the DU of the child IAB node (“Child DU”).

The parent IAB node may transmit downlink data to the child IAB node on the first set of resources 710. The first set of resources 710 may be configured as hard for the parent DU to allow the parent DU to decide whether to use the resources 710 to transmit downlink data to the child IAB node regardless of operation of the MTY of the parent IAB. The first set of resources 710 may be configured as DL for the child MT to receive the downlink data from the parent DU. The first set of resources 710 may be configured as NA for the child DU to prevent the child DU from interfering with the child MT receiving the downlink data from the parent DU.

The child IAB node may transmit downlink data to a child entity, such as another IAB node or a UE, on the second set of resources 720. The child DU may be configured as hard for the second set of resources 720, and the parent DU may be configured as NA for the second set of resources 720 so that the child MT and the parent DU may not communicate with one another on the second set of resources 720.

The child IAB node may transmit uplink data to the parent IAB node on the third set of resources 730. The third set of resources 730 may be configured as UL for the child MT to transmit the uplink data to the parent DU. The third set of resources 730 may be configured as NA for the child DU to prevent the child DU from interfering with the child MT transmitting the uplink data to the parent DU. The third set of resources 730 may be configured as hard for the parent DU so that the parent DU can decide whether to use the resources to receive uplink data from the child node regardless of operation of the MT of the parent IAB apparatus.

As the child IAB node is communicating utilizing its MT on the first set of resources 710 and communicating utilizing its DU on the second set of resources 720, the child IAB node performs a transition between its MT and DU at the time 714 between the two sets of resources. Similarly, as the child IAB node is communicating utilizing its DU on the second set of resources 720 and communicating utilizing its MT on the third set of resources 730, the child IAB node performs a transition between its DU and its MT at the time 724 between the two sets of resources.

The parent IAB apparatus and the child IAB node may utilize guard symbols at transition times (e.g., time 714 and time 724). A guard symbol may be a resource on which nothing is transmitted. An IAB node may utilize one or more different component (e.g., different transmitter(s), different receiver(s), or different antenna(s)) and/or different analog beams for its MT and its DU. The guard symbols may provide time for the IAB node to switch between components used for the MT and components used for the DU. The guard symbols may also prevent conflicts due where an MT and a DU of an IAB node are both supposed to be operating at the same time (e.g., due to propagation delay or timing advance).

For example, as illustrated in FIG. 7 , although the parent DU transmits downlink data on the first set of resources 710, the transmission may actually be received at the child IAB node on resources 712, slightly delayed from the first set of resources 710. Some of the resources 712 overlap with the second set of resources 720 on which the child MT is configured to transmit downlink data to another device. Guard symbols at the end of the resources 710 provided by the parent DU and/or at the beginning of the resources 740 provided by the child DU may allow the child node to transition from use of the MT to receive downlink data to use of the DU to transmit downlink data without conflict. Uplink data transmitted on resources 732 from the child IAB node to the parent DU may face similar challenges, and guard symbols at the end of resources 740 provided by the child DU and/or at the beginning of resources 730 provided by the parent DU may allow the child IAB node to transition from use of the DU to transmit downlink data to use of the MT to transmit uplink data without conflict.

FIG. 8 is a table 800 illustrating IAB node transition types. A transition type may be based on the configuration of the resources immediately before and immediately after the transition. A given resource may be configured for use by the MT or for use by the DU. Resources configured for use by the MT may be configured for receiving downlink data from a parent (DL Rx) or for transmitting uplink data to the parent (UL Tx). Resources configured for the DU may be configured for transmitting downlink data to a child (DL Tx) or for receiving uplink data from the child (UL Rx).

A transition from using the MT to receive downlink data (DL Rx) to using the DU to transmit downlink data (DL Tx) may be referred to as a Type 1 transition. A transition from using the MT to receive downlink data (DL Rx) to using the DU to receive uplink data (UL Rx) may be referred to as a Type 2 transition. A transition from using the MT to transmit uplink data (UL Tx) to using the DU to transmit downlink data (DL Tx) may be referred to as a Type 3 transition. A transition from using the MT to transmit uplink data (UL Tx) to using the DU to receive uplink data (UL Rx) may be referred to as a Type 4 transition. A transition from using the DU to transmit downlink data (DL Tx) to using the MT to receive downlink data (DL Rx) may be referred to as a Type 5 transition. A transition from using the DU to transmit downlink data (DL Tx) to using the MT to transmit uplink data (UL Tx) may be referred to as a Type 6 transition. A transition from using the DU to receive uplink data (UL Rx) to using the MT to receive downlink data (DL Rx) may be referred to as a Type 7 transition. A transition from using the DU to receive uplink data (UL Rx) to using the MT to transmit uplink data (UL Tx) may be referred to as a Type 8 transition.

The number of guard symbols provided at a transition time may be based on the transition type of the transition. The number of symbols provided for a given transition type may be based on the switching and signal propagation requirements for the transition. For example, in some aspects, transitions of Type 1, 4, 5, and 8 may receive guard symbols to provide for switching from the transmitter to the receiver. In some aspects, transitions of Type 1 and 2 may receive guard symbols to provide for a propagation delay based on the distance from the parent IAB apparatus. In some aspects, transitions of Type 7 and 8 may receive guard symbols to provide for a propagation delay based on the distance from the child IAB node or UE. In some aspects, transitions of Types 1-8 may receive guard symbols to provide for switching antennas. The number of guard symbols provided for a given transition type may be based on a GuardSymbolsDesired signal transmitted from the child IAB node to the parent IAB apparatus and on a GuardSymbolsProvided signal transmitted from the parent IAB apparatus to the child IAB node, which will be discussed further below.

FIG. 9 is a communication diagram 900 illustrating guard symbol signaling between a child IAB node 902 and a parent IAB apparatus 904. The guard symbols for a transition may be located at the resources immediately before the transition, the resources immediately after the transition, or may be split between both the resources immediately before and immediately after the transition. The child IAB node 902 and the parent IAB apparatus 904 may communicate to determine how many of the guard symbols will be provided by the child IAB node 902 and how many of the guard symbols will be provided by the parent IAB apparatus 904.

The child IAB node 902 may have a set of GuardSymbolDesired values corresponding to different transition types, such as the Types 1-8 described above with respect to FIG. 8 . The GuardSymbolsDesired values may identify the number of guard symbols which should be provided for the child IAB node 902 to perform a transition of that type. The child IAB node 902 may transmit a GuardSymbolsDesired signal 910 to the parent IAB apparatus 904. The GuardSymbolsDesired signal 910 may include some or all of the GuardSymbolsDesired values corresponding to transmission types. In some aspects, the GuardSymbolsDesired signal 910 may include one or more media access control (MAC) control elements (MAC CEs). In some aspects, if a value is not included for a transition type, zero guard symbols may be provided for that transition type.

The parent IAB apparatus 904 may transmit a GuardSymbolsProvided signal 920 to the child IAB node 902. The GuardSymbolsProvided signal 920 may include GuardSymbolsProvided values corresponding to transition types, such as transition Types 1-8. The GuardSymbolsProvided value for a transition type may indicate a number of guard symbols which the parent IAB apparatus 904 will provide when the child IAB node 902 performs a transmission of that type. The value included in the GuardSymbolsProvided signal 920 for a transition type may be equal to or less than the value included in the GuardSymbolsDesired signal 910 for that transition type. In some aspects, the value included in the GuardSymbolsProvided signal 920 may be based on resource utilization and/or performance impact. In some aspects, if no value is included for a transition type, the parent IAB apparatus 904 may provide zero guard symbols for transitions of that type.

When the child IAB node 902 performs a transition between use of its MT and use of its DU, the child IAB node 902 and the parent IAB apparatus 904 will provide guard symbols based on the GuardSymbolsDesired and GuardSymbolsProvided values. As a transition is between use of the DU of the child IAB node 902 and use of the MT of the child IAB node 902, the transition will be adjacent to one set of resources allocated to the MT for communication between the child IAB node 902 and the parent IAB apparatus 904, and a second set of resources allocated to the DU for communication between the child IAB node 902 and a child if the child IAB node 902. The parent IAB apparatus 904 and the child IAB node 902 will not transmit or receive on guard symbols allocated to the MT, the number of which will be based on the GuardSymbolsProvided value for that transition type. The child IAB node 902 will not transmit or receive on guard symbols allocated to the DU, the number of which will be based on the value for GuardSymbolsProvided and the value for GuardSymbolsDesired for that transition type. In some aspects, the number of guard symbols provided on the DU by the child IAB node 902 may be the difference between the GuardSymbolsDesired and the GuardSymbolsProvided.

For example, FIG. 10A is a diagram 1000 illustrating guard symbols at a transition from DU to MT. The child IAB node may transition from use of its DU to use of its MT at a transition time 1010. The GuardSymbolsDesired value for transitions of the transition type may be four, and the GuardSymbolsProvided value may be two. Because the GuardSymbolsProvided value is two, neither the parent IAB apparatus nor the child IAB node transmit on the two symbols 1020 following the transition time 1010. Because the GuardSybolsDesired value is four and two guard symbols are being provided on the resources after the transition time 1010, the child IAB node may not transmit or receive on the two symbols before the transition time 1010, resulting in four guard symbols 1030 for the transition. The child IAB node may switch from operation of its DU to operation of its MT during the time associated with the four guard symbols 1030.

In another example, FIG. 10B is a diagram 1050 illustrating guard symbols at a transition from MT to DU. The child IAB node may transition from use of its MT to use of its DU at a transition time 1060. The GuardSymbolsDesired value for transitions of the transition type may be four, and the GuardSymbolsProvided value may be two. Because the GuardSymbolsProvided value is two, neither the parent IAB apparatus nor the child IAB node transmit on the two symbols 1070 before the transition time 1060. Because the GuardSybolsDesired value is four and two guard symbols are being provided on the resources before the transition time 1060, the child IAB node may not transmit or receive on the two symbols after the transition time 1060, resulting in four guard symbols 1080 for the transition. The child IAB node may switch from operation of its MT to operation of its DU during the time associated with the four guard symbols 1080.

Referring again to FIG. 8 , the transition type of a transition is based on whether the resources before and after the transition time have a DL resource type or an UL resource type, and the number of guard symbols provided for that transition is based on its transition type. However, a resource may be allocated with a F resource type, and may later be converted to a DL or an UL resource type through slot format indication (SFI) or dynamic scheduling. Where a resource allocated to a DU of a child IAB node initially has a F resource type, the parent IAB apparatus of the child IAB node may not know whether that resource allocated to the DU of the child IAB node will have a DL or an UL resource type at the time of the transition. Accordingly, the parent IAB apparatus may not know the type of the transition, and may not know how many guard symbols it should provide for that transition. The child IAB node may not know how many guard symbols the parent IAB node will provide for the transition, so the child IAB node may not be able to determine how many additional guard symbols it should provide to meet its GuardSymbolsDesired value for that transition.

Where a resource allocated to an MT of a child IAB node initially has a F resource type, the parent IAB apparatus may know whether the resource is later converted to a DL or an UL resource type. For example, the parent IAB apparatus may determine whether the resource is converted to a DL resource type or converted to an UL resource type. However, in some aspects, the child IAB node may receive a scheduling grant scheduling the resources at the transition time prior to the parent IAB apparatus determining whether the resource is converted to a DL resource type or to an UL resource type. Because the child IAB node does not know whether the resource allocated to the MT of the child IAB node will be converted to UL or to DL, it may not know what transition type the transition will be. The child IAB node may not know how many guard symbols the parent IAB apparatus will provide, and may therefore not know whether the child IAB node should provide guard symbols or how many guard symbols it should provide for the transition.

In some aspects, when a child IAB node performs a transition and the resource adjacent to the transition time allocated to a DU of the child IAB node has an F resource type, the parent IAB apparatus may determine the number of guard symbols to provide based on the resource having the F resource type (e.g., instead of based on whether the resource is converted to UL or DL) and the transition types illustrated in FIG. 8 . In some aspects, the parent IAB node may determine a first transition type where the F resource is replaced with a DL resource, may determine a second transition type where the F resource is replaced with an UL resource, and may select one of the guard symbol provided value for the first transition type and the guard symbol provided value for the second transition type. For example, where the child IAB node is transitioning from UL resources on its MT to F resources on its DU, the parent IAB node may determine the first transition type to be the Type 3 transition (from UL resources on the MT to DL resources on the DU) and may determine the second transition type to be the Type 4 transition (from UL resources on the MT to UL resources on the DU), and may select one of the guard symbols provided values for Type 3 transitions and Type 4 transitions. In some aspects, the parent IAB apparatus may select the higher of the two values. In some aspects, the parent IAB apparatus may select the lower of the two values.

In some aspects, when a child IAB node performs a transition and the resource adjacent to the transition time allocated to a DU of the child IAB node has an F resource type, the parent IAB apparatus may determine to provide zero guard symbols for that transition.

In some aspects, the CU of the IAB donor may provide the parent IAB apparatus with the child IAB node's configuration on cell-specific signals or channels. When a child IAB node performs a transition and the resource adjacent to the transition time allocated to the DU of the child IAB node has an F resource type, if the cell-specific signals or channels of the child IAB-node fall within the F resources, the parent IAB-node may assume that this F resource of child IAB-node DU will be converted to a DL or UL resource type based on whether the cell-specific signal or channel is a DL or UL signal or channel, and may determine the number of guard symbols based on the transition type associated with the assumed resource type For example, where the child IAB node is transitioning from UL resources on its MT to F resources on its DU, the parent IAB node may determine that a cell-specific signal or a cell-specific channel lies within the F resources on the DU, may determine that the cell-specific signal or cell-specific channel is an uplink signal or channel (e.g., a physical random access channel (PRACH) or a physical uplink control channel (PUCCH) scheduling request (SR)), may assume an UL resource type for the DU resources, and may provide guard symbols based on the number of guard symbols to be provided for a transition with transition Type 4 (from UL resources on the MT to UL resources on the DU).

In some aspects, when a child IAB node performs a transition and the resource adjacent to the transition time allocated to a MT of the child IAB node has an F resource type, the parent IAB apparatus may determine the number of guard symbols to provide based on the resource having the F resource type (e.g., instead of based on whether the resource is converted to UL or DL) and the transition types illustrated in FIG. 8 . In some aspects, the parent IAB node may determine a first transition type where the F resource is replaced with a DL resource, may determine a second transition type where the F resource is replaced with an UL resource, and may select one of the guard symbol provided value for the first transition type and the guard symbol provided value for the second transition type. For example, where the child IAB node is transitioning from F resources on its MT to UL resources on its DU, the parent IAB node may determine the first transition type to be the Type 2 transition (from DL resources on the MT to UL resources on the DU) and may determine the second transition type to be the Type 4 transition (from UL resources on the MT to UL resources on the DU), and may select one of the guard symbols provided values for Type 3 transitions and Type 4 transitions. In some aspects, the parent IAB apparatus may select the higher of the two values. In some aspects, the parent IAB apparatus may select the lower of the two values.

In some aspects, when a child IAB node performs a transition and the resource adjacent to the transition time allocated to a MT of the child IAB node is semi-statically configured to have an F resource type, the parent IAB apparatus may determine to provide zero guard symbols for the transition. In some aspects, when a child IAB node performs a transition and the resource adjacent to the transition time allocated to a MT of the child IAB node is indicated as a F resource type through SFI, the parent IAB apparatus may determine to provide zero guard symbols for the transition.

In some aspects, when a child IAB node performs a transition and the resource adjacent to the transition time allocated to a MT of the child IAB node has an F resource type, the parent IAB apparatus may determine the number of guard symbols to provide based on whether the resource with the F resource type is converted to DL or to UL from semi-static allocation or dynamic allocation. For example, if a downlink semi-static allocation (e.g. a synchronization signal block (SSB), a channel state information reference signal (CSI-RS), PDCCH, PDSCH semi-persistent scheduling (SPS)) lies within the resource with the F resource type, the resource is converted to DL and the parent IAB apparatus may determine the number of guard symbols based on the DL resource type. If a dynamic DCI grant schedules a downlink transmission at a resource with the F resource type, the resource is converted to DL and the parent IAB apparatus may determine the number of guard symbols based on the DL resource type. If an uplink semi-static allocation (e.g. PRACH, SRS, PUCCH, PUSCH SPS etc.) lies within the resource with the F resource type, the resource is converted to UL and the parent IAB apparatus may determine the number of guard symbols based on the UL resource type. If a dynamic DCI grant schedules an uplink transmission at a resource with the F resource type, the resource is converted to UL and the parent IAB apparatus may determine the number of guard symbols based on the UL resource type.

FIG. 11 is a table 1100 illustrating IAB node transition types with flexible DU resources. In some aspects, in addition to the transitions types discussed above with respect to FIG. 8 , the child IAB node and the parent IAB apparatus may include GuardSymbolsDesired and GuardSymbolsProvided values corresponding to transition types in which the resources allocated to the DU adjacent to the transition time have a flexible (F) resource type.

A transition Type 9 may be a transition type where the child IAB node transitions from DL resources allocated to the MT to F resources allocated to the DU. A transition Type 10 may be a transition type where the child IAB node transitions from UL resources allocated to the MT to F resources allocated to the DU. A transition Type 11 may be a transition type where the child IAB node transitions from F resources allocated to the DU to DL resources allocated to the MT. A transition Type 12 may be a transition type where the child IAB node transitions from F resources allocated to the DU to UL resources allocated to the MT.

The child IAB node may include values for a number of guard symbols to be provided when the child IAB node performs transitions of Types 9-12 when transmitting the GuardSymbolsDesired signal to the parent IAB apparatus. The parent apparatus may include values for a number of guard symbols which the parent will provide when the child IAB node performs transitions of Types 9-12 when transmitting the GuardSymbolsProvided signal to the child IAB node. Instead of determining how many guard symbols to provide based on whether the F type resources allocated to the DU are converted to UL or DL, the child IAB node and the parent IAB apparatus may recognize these transitions as separate transition types and provide guard symbols based on the their associated GuardSymbolsDesired and GuardSymbolsProvided values.

FIG. 12 is a table 1200 illustrating IAB node transition types with flexible MT resources. In some aspects, in addition to the transitions types discussed above with respect to FIG. 8 , the child IAB node and the parent IAB apparatus may include GuardSymbolsDesired and GuardSymbolsProvided values corresponding to transition types in which the resources allocated to the MT adjacent to the transition time have a F resource type.

A transition Type 9 may be a transition type where the child IAB node transitions from F resources allocated to the MT to DL resources allocated to the DU. A transition Type 10 may be a transition type where the child IAB node transitions from F resources allocated to the MT to UL resources allocated to the DU. A transition Type 11 may be a transition type where the child IAB node transitions from DL resources allocated to the DU to F resources allocated to the MT. A transition Type 12 may be a transition type where the child IAB node transitions from UL resources allocated to the DU to F resources allocated to the MT.

The child IAB node may include values for a number of guard symbols to be provided when the child IAB node performs transitions of Types 9-12 when transmitting the GuardSymbolsDesired signal to the parent IAB apparatus. The parent apparatus may include values for a number of guard symbols which the parent will provide when the child IAB node performs transitions of Types 9-12 when transmitting the GuardSymbolsProvided signal to the child IAB node. Instead of determining how many guard symbols to provide based on whether the F type resources allocated to the MT are converted to UL or DL, the child IAB node and the parent IAB apparatus may recognize these transitions as separate transition types and provide guard symbols based on the their associated GuardSymbolsDesired and GuardSymbolsProvided values.

FIG. 13 is a table 1300 illustrating IAB node transition types with flexible MT resources and flexible DU resources. In some aspects, in addition to the transitions types discussed above with respect to FIG. 8 , the child IAB node and the parent IAB apparatus may include GuardSymbolsDesired and GuardSymbolsProvided values corresponding to transition types in which the resources allocated to the DU adjacent to the transition time have a F resource type or the resources allocated to the MT adjacent to the transition time have a F resource type.

A transition Type 9 may be a transition type where the child IAB node transitions from DL resources allocated to the MT to F resources allocated to the DU. A transition Type 10 may be a transition type where the child IAB node transitions from UL resources allocated to the MT to F resources allocated to the DU. A transition Type 11 may be a transition type where the child IAB node transitions from F resources allocated to the MT to DL resources allocated to the DU. A transition Type 12 may be a transition type where the child IAB node transitions from F resources allocated to the MT to UL resources allocated to the DU. A transition Type 13 may be a transition type where the child IAB node transitions from F resources allocated to the MT to F resources allocated to the DU.

A transition Type 14 may be a transition type where the child IAB node transitions from DL resources allocated to the DU to F resources allocated to the MT. A transition Type 15 may be a transition type where the child IAB node transitions from UL resources allocated to the DU to F resources allocated to the MT. A transition Type 16 may be a transition type where the child IAB node transitions from F resources allocated to the DU to DL resources allocated to the MT. A transition Type 17 may be a transition type where the child IAB node transitions from F resources allocated to the DU to UL resources allocated to the MT. A transition Type 18 may be a transition type where the child IAB node transitions from F resources allocated to the DU to F resources allocated to the MT.

The child IAB node may include values for a number of guard symbols to be provided when the child IAB node performs transitions of Types 9-18 when transmitting the GuardSymbolsDesired signal to the parent IAB apparatus. The parent apparatus may include values for a number of guard symbols which the parent will provide when the child IAB node performs transitions of Types 9-18 when transmitting the GuardSymbolsProvided signal to the child IAB node. Instead of determining how many guard symbols to provide based on whether the F type resources allocated to the MT or to the DU are converted to UL or DL, the child IAB node and the parent IAB apparatus may recognize these transitions as separate transition types and provide guard symbols based on the their associated GuardSymbolsDesired and GuardSymbolsProvided values.

FIG. 14 is a flowchart 1400 of a method of wireless communication. The method may be performed by an IAB apparatus (e.g., the parent IAB apparatus 904, the IAB donor 410, 510, or 610, the IAB node 420, 520, or 620). The IAB apparatus may be an IAB donor or an IAB node.

At 1402, the IAB apparatus transmits a set of values to a child IAB node. Each value of the set of values corresponds to a transition type for a transition of the child IAB node between use of a mobile terminal of the child IAB node and use of a distributed unit of the child IAB node. A transition type corresponds to a first resource type for resources immediately before a transition time and to a second resource type for resources immediately after the transition time. In some aspects, the first resource type may be allocated for use by a MT of the child IAB node, and the second resource type may be allocated for use by a DU of the child IAB node. In some aspects, the second resource type may be allocated for use by a MT of the child IAB node, and the first resource type may be allocated for use by a DU of the child IAB node. In some aspects, the set of values may include a first value corresponding to a transition wherein the symbols immediately before the transition or immediately after the transition have the resource type of flexible, and the number of guard symbols may be based on the first value.

At 1404, the IAB apparatus determines that the child IAB node will perform a transition at a transition time. A symbol immediately before the transition or immediately after the transition has a resource type of flexible.

At 1406, the IAB apparatus provides a number of guard symbols at the transition time. The number of guard symbols is based on determining that the symbol immediately before the transition or immediately after the transition has the resource type of flexible. In some aspects, the symbol immediately before or immediately after the transition may have the resource type of flexible and may be allocated to the distributed unit, and the number of guard symbols may be based on a value of the set of values corresponding to a transition type without a flex symbol immediately before or immediately after the transition. In some aspects, the symbol immediately before or immediately after the transition may have the resource type of flexible and may be allocated to the mobile terminal, and the number of guard symbols may be based on a value of the set of values corresponding to a transition type without a flex symbol immediately before or immediately after the transition. In some aspects, the value of the set of values is selected based on whether the symbol having the flexible type is converted to downlink or to uplink.

In some aspects, the number of guard symbols may be a higher value selected from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the distributed unit and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the distributed unit.

In some aspects, the number of guard symbols may be a lower value selected from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the distributed unit and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the distributed unit.

In some aspects, the number of guard symbols may be a higher value selected from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal.

In some aspects, the number of guard symbols may be a lower value selected from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal.

FIG. 15 is a flowchart 1500 of a method of wireless communication. The method may be performed by an IAB node (e.g., the child IAB node 902, the IAB node 420, 520, or 620).

At 1502, the IAB node receives a set of values from a parent IAB apparatus. Each value of the set of values corresponds to a transition type for a transition of the IAB node between use of a mobile terminal of the IAB node and use of a distributed unit of the IAB node. A transition type corresponds to a first resource type for resources immediately before a transition time and to a second resource type for resources immediately after the transition time. In some aspects, the first resource type may be allocated for use by a MT of the IAB node, and the second resource type may be allocated for use by a DU of the IAB node. In some aspects, the second resource type may be allocated for use by a MT of the IAB node, and the first resource type may be allocated for use by a DU of the IAB node. In some aspects, the set of values may include a first value corresponding to a transition wherein the symbols immediately before the transition or immediately after the transition have the resource type of flexible, and the number of guard symbols may be based on the first value.

At 1504, the IAB node determines to perform a transition at a transition time. A symbol immediately before the transition or immediately after the transition has a resource type of flexible.

At 1506, the IAB node receives a number of guard symbols at the transition time. The number of guard symbols is based on determining that the symbol immediately before the transition or immediately after the transition has the resource type of flexible. In some aspects, the symbol immediately before or immediately after the transition may have the resource type of flexible and may be allocated to the distributed unit, and the number of guard symbols may be based on a value of the set of values corresponding to a transition type without a flex symbol immediately before or immediately after the transition. In some aspects, the symbol immediately before or immediately after the transition may have the resource type of flexible and may be allocated to the mobile terminal, and the number of guard symbols may be based on a value of the set of values corresponding to a transition type without a flex symbol immediately before or immediately after the transition. In some aspects, the value of the set of values is selected based on whether the symbol having the flexible type is converted to downlink or to uplink.

In some aspects, the IAB node may select a higher value from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the distributed unit and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the distributed unit, and the number of guard symbols may be based on the selected value.

In some aspects, the IAB node may select a lower value from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the distributed unit and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the distributed unit, and the number of guard symbols may be based on the selected value.

In some aspects, the IAB node may select a higher value from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal, and the number of guard symbols may be based on the selected value.

In some aspects, the IAB node may select a lower value from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal, and the number of guard symbols may be based on the selected value.

FIG. 16 is a flowchart 1600 of a method of wireless communication. The method may be performed by an IAB node (e.g., the child IAB node 902, the IAB node 420, 520, or 620).

At 1602, the IAB node transmits a set of values to a parent IAB apparatus. Each value of the set of values corresponds to a transition type for a transition of the IAB node between use of a mobile terminal of the IAB node and use of a distributed unit of the IAB node. A transition type corresponds to a first resource type for resources immediately before a transition time and to a second resource type for resources immediately after the transition time. In some aspects, the first resource type may be allocated for use by a MT of the IAB node, and the second resource type may be allocated for use by a DU of the IAB node. In some aspects, the second resource type may be allocated for use by a MT of the IAB node, and the first resource type may be allocated for use by a DU of the IAB node. In some aspects, the set of values may include a first value corresponding to a transition wherein the symbols immediately before the transition or immediately after the transition have the resource type of flexible, and the number of guard symbols may be based on the first value.

At 1604, the IAB node determines to perform a transition at a transition time. A symbol immediately before the transition or immediately after the transition has a resource type of flexible.

At 1606, the IAB node receives a number of guard symbols from the parent IAB apparatus at the transition time. The number of guard symbols is based on determining that the symbol immediately before the transition or immediately after the transition has the resource type of flexible. In some aspects, the symbol immediately before or immediately after the transition may have the resource type of flexible and may be allocated to the distributed unit, and the number of guard symbols may be based on a value of the set of values corresponding to a transition type without a flex symbol immediately before or immediately after the transition. In some aspects, the symbol immediately before or immediately after the transition may have the resource type of flexible and may be allocated to the mobile terminal, and the number of guard symbols may be based on a value of the set of values corresponding to a transition type without a flex symbol immediately before or immediately after the transition. In some aspects, the value of the set of values is selected based on whether the symbol having the flexible type is converted to downlink or to uplink.

In some aspects, the number of guard symbols may be a higher value selected from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the distributed unit and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the distributed unit.

In some aspects, the number of guard symbols may be a lower value selected from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the distributed unit and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the distributed unit.

In some aspects, the number of guard symbols may be a higher value selected from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal.

In some aspects, the number of guard symbols may be a lower value from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal.

FIG. 17 is a flowchart 1700 of a method of wireless communication. The method may be performed by an IAB apparatus (e.g., the parent IAB apparatus 904, the IAB donor 410, 510, or 610, the IAB node 420, 520, or 620). The IAB apparatus may be an IAB donor or an IAB node.

At 1702, the IAB apparatus receives a set of values from a child IAB node.

Each value of the set of values corresponds to a transition type for a transition of the child IAB node between use of a mobile terminal of the child IAB node and use of a distributed unit of the child IAB node. A transition type corresponds to a first resource type for resources immediately before a transition time and to a second resource type for resources immediately after the transition time. In some aspects, the first resource type may be allocated for use by a MT of the child IAB node, and the second resource type may be allocated for use by a DU of the child IAB node. In some aspects, the second resource type may be allocated for use by a MT of the child IAB node, and the first resource type may be allocated for use by a DU of the child IAB node. In some aspects, the set of values may include a first value corresponding to a transition wherein the symbols immediately before the transition or immediately after the transition have the resource type of flexible, and the number of guard symbols may be based on the first value.

At 1704, the IAB apparatus determines that the child IAB node will perform a transition at a transition time. A symbol immediately before the transition or immediately after the transition has a resource type of flexible.

At 1706, the IAB apparatus provides a number of guard symbols at the transition time. The number of guard symbols is based on determining that the symbol immediately before the transition or immediately after the transition has the resource type of flexible. In some aspects, the symbol immediately before or immediately after the transition may have the resource type of flexible and may be allocated to the distributed unit, and the number of guard symbols may be based on a value of the set of values corresponding to a transition type without a flex symbol immediately before or immediately after the transition. In some aspects, the symbol immediately before or immediately after the transition may have the resource type of flexible and may be allocated to the mobile terminal, and the number of guard symbols may be based on a value of the set of values corresponding to a transition type without a flex symbol immediately before or immediately after the transition. In some aspects, the value of the set of values is selected based on whether the symbol having the flexible type is converted to downlink or to uplink.

In some aspects, the IAB node may select a higher value from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the distributed unit and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the distributed unit, and the number of guard symbols may be based on the selected value.

In some aspects, the IAB node may select a lower value from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the distributed unit and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the distributed unit, and the number of guard symbols may be based on the selected value.

In some aspects, the IAB node may select a higher value from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal, and the number of guard symbols may be based on the selected value.

In some aspects, the IAB node may select a lower value from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal, and the number of guard symbols may be based on the selected value.

FIG. 18 is a diagram 1800 illustrating an example of a hardware implementation for an apparatus 1802. The apparatus 1802 is a BS and includes a baseband unit 1804. The baseband unit 1804 may communicate through a cellular RF transceiver with the UE 104. The baseband unit 1804 may include a computer-readable medium/memory. The baseband unit 1804 is responsible for general processing, including the execution of software stored on the computer-readable medium/memory. The software, when executed by the baseband unit 1804, causes the baseband unit 1804 to perform the various functions described supra. The computer-readable medium/memory may also be used for storing data that is manipulated by the baseband unit 1804 when executing software. The baseband unit 1804 further includes a reception component 1830, a communication manager 1832, and a transmission component 1834. The communication manager 1832 includes the one or more illustrated components. The components within the communication manager 1832 may be stored in the computer-readable medium/memory and/or configured as hardware within the baseband unit 1804. The baseband unit 1804 may be a component of the BS 310 and may include the memory 376 and/or at least one of the TX processor 316, the RX processor 370, and the controller/processor 375.

The apparatus 1802 may be a part of an IAB network and may be or may include an IAB donor and/or an IAB node.

In some aspects, the communication manager 1832 includes a value transmission component 1840 that transmits a set of values to a child IAB node, each value of the set of values corresponding to a transition type for a transition of the child IAB node between use of a mobile terminal of the child IAB node and use of a distributed unit of the child IAB node, a transition type corresponding to a first resource type for resources immediately before a transition time and to a second resource type for resources immediately after the transition time, e.g., as described in connection with 1402 of FIG. 14 . The communication manager 1832 further includes a transition type determination component 1842 that determines that the child IAB node will perform a transition at a transition time, wherein a symbol immediately before the transition or immediately after the transition has a resource type of flexible, e.g., as described in connection with 1404 of FIG. 14 . The communication manager 1832 further includes a guard symbol provision component 1846 that provides a number of guard symbols at the transition time, the number of guard symbols being based on determining that the symbol immediately before the transition or immediately after the transition has the resource type of flexible, e.g., as described in connection with 1406 of FIG. 14 .

In some aspects, the communication manager 1832 includes a value reception component 1850 that receives a set of values from a parent IAB apparatus, each value of the set of values corresponding to a transition type for a transition of the IAB node between use of a mobile terminal of the IAB node and use of a distributed unit of the IAB node, a transition type corresponding to a first resource type for resources immediately before a transition time and to a second resource type for resources immediately after the transition time, e.g., as described in connection with 1502 of FIG. 15 . The communication manager 1832 further includes a transition type determination component 1852 that determines to perform a transition at a transition time, wherein a symbol immediately before the transition or immediately after the transition has a resource type of flexible, e.g., as described in connection with 1504 of FIG. 15 . The communication manager 1832 further includes a guard symbol reception component 1856 that receives a number of guard symbols at the transition time, the number of guard symbols being based on determining that the symbol immediately before the transition or immediately after the transition has the resource type of flexible, e.g., as described in connection with 1506 of FIG. 15 .

In some aspects, the communication manager 1832 includes a value transmission component 1860 that transmits a set of values to a parent IAB apparatus, each value of the set of values corresponding to a transition type for a transition of the IAB node between use of a mobile terminal of the IAB node and use of a distributed unit of the IAB node, a transition type corresponding to a first resource type for resources immediately before a transition time and to a second resource type for resources immediately after the transition time, e.g., as described in connection with 1602 of FIG. 16 . The communication manager 1832 further includes a transition type determination component 1862 that determines to perform a transition at a transition time, wherein a symbol immediately before the transition or immediately after the transition has a resource type of flexible, e.g., as described in connection with 1604 of FIG. 16 . The communication manager 1832 further includes a guard symbol reception component 1866 that receives a number of guard symbols from the parent IAB apparatus at the transition time, the number of guard symbols being based on determining that the symbol immediately before the transition or immediately after the transition has the resource type of flexible, e.g., as described in connection with 1606 of FIG. 16 .

In some aspects, the communication manager 1832 includes a value reception component 1870 that receives a set of values from a child IAB node, each value of the set of values corresponding to a transition type for a transition of the child IAB node between use of a mobile terminal of the child IAB node and use of a distributed unit of the child IAB node, a transition type corresponding to a first resource type for resources immediately before a transition time and to a second resource type for resources immediately after the transition time, e.g., as described in connection with 1702 of FIG. 17 . The communication manager 1832 further includes a transition type determination component 1872 that determines that the child IAB node will perform a transition at a transition time, wherein a symbol immediately before the transition or immediately after the transition has a resource type of flexible, e.g., as described in connection with 1704 of FIG. 17 . The communication manager 1832 further includes a guard symbol provision component 1876 that provides a number of guard symbols at the transition time, the number of guard symbols being based on determining that the symbol immediately before the transition or immediately after the transition has the resource type of flexible, e.g., as described in connection with 1706 of FIG. 17 .

The apparatus may include additional components that perform each of the blocks of the algorithm in the aforementioned flowcharts of FIGS. 14-17 . As such, each block in the aforementioned flowcharts of FIGS. 14-17 may be performed by a component and the apparatus may include one or more of those components. The components may be one or more hardware components specifically configured to carry out the stated processes/algorithm, implemented by a processor configured to perform the stated processes/algorithm, stored within a computer-readable medium for implementation by a processor, or some combination thereof.

In some configurations, the apparatus 1802, and in particular the baseband unit 1804, includes means for transmitting a set of values to a child IAB node, each value of the set of values corresponding to a transition type for a transition of the child IAB node between use of a mobile terminal of the child IAB node and use of a distributed unit of the child IAB node, a transition type corresponding to a first resource type for resources immediately before a transition time and to a second resource type for resources immediately after the transition time; means for determining that the child IAB node will perform a transition at a transition time, wherein a symbol immediately before the transition or immediately after the transition has a resource type of flexible; and means for providing a number of guard symbols at the transition time, the number of guard symbols being based on determining that the symbol immediately before the transition or immediately after the transition has the resource type of flexible.

In some configurations, the apparatus 1802, and in particular the baseband unit 1804, includes means for receiving a set of values from a parent IAB apparatus, each value of the set of values corresponding to a transition type for a transition of the IAB node between use of a mobile terminal of the IAB node and use of a distributed unit of the IAB node, a transition type corresponding to a first resource type for resources immediately before a transition time and to a second resource type for resources immediately after the transition time; means for determining to perform a transition at a transition time, wherein a symbol immediately before the transition or immediately after the transition has a resource type of flexible; and means for receiving a number of guard symbols at the transition time, the number of guard symbols being based on determining that the symbol immediately before the transition or immediately after the transition has the resource type of flexible.

In some configurations, the apparatus 1802, and in particular the baseband unit 1804, includes means for transmitting a set of values to a parent IAB apparatus, each value of the set of values corresponding to a transition type for a transition of the IAB node between use of a mobile terminal of the IAB node and use of a distributed unit of the IAB node, a transition type corresponding to a first resource type for resources immediately before a transition time and to a second resource type for resources immediately after the transition time; means for determining to perform a transition at a transition time, wherein a symbol immediately before the transition or immediately after the transition has a resource type of flexible; and means for receiving a number of guard symbols from the parent IAB apparatus at the transition time, the number of guard symbols being based on determining that the symbol immediately before the transition or immediately after the transition has the resource type of flexible.

In some configurations, the apparatus 1802, and in particular the baseband unit 1804, includes means for receiving a set of values from a child IAB node, each value of the set of values corresponding to a transition type for a transition of the child IAB node between use of a mobile terminal of the child IAB node and use of a distributed unit of the child IAB node, a transition type corresponding to a first resource type for resources immediately before a transition time and to a second resource type for resources immediately after the transition time; means for determining that the child IAB node will perform a transition at a transition time, wherein a symbol immediately before the transition or immediately after the transition has a resource type of flexible; and means for providing a number of guard symbols at the transition time, the number of guard symbols being based on determining that the symbol immediately before the transition or immediately after the transition has the resource type of flexible.

The aforementioned means may be one or more of the aforementioned components of the apparatus 1802 configured to perform the functions recited by the aforementioned means. As described supra, the apparatus 1802 may include the TX Processor 316, the RX Processor 370, and the controller/processor 375. As such, in one configuration, the aforementioned means may be the TX Processor 316, the RX Processor 370, and the controller/processor 375 configured to perform the functions recited by the aforementioned means.

It is understood that the specific order or hierarchy of blocks in the processes/flowcharts disclosed is an illustration of example approaches. Based upon design preferences, it is understood that the specific order or hierarchy of blocks in the processes/flowcharts may be rearranged. Further, some blocks may be combined or omitted. The accompanying method claims present elements of the various blocks in a sample order, and are not meant to be limited to the specific order or hierarchy presented.

The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects. Unless specifically stated otherwise, the term “some” refers to one or more. Combinations such as “at least one of A, B, or C,” “one or more of A, B, or C,” “at least one of A, B, and C,” “one or more of A, B, and C,” and “A, B, C, or any combination thereof” include any combination of A, B, and/or C, and may include multiples of A, multiples of B, or multiples of C. Specifically, combinations such as “at least one of A, B, or C,” “one or more of A, B, or C,” “at least one of A, B, and C,” “one or more of A, B, and C,” and “A, B, C, or any combination thereof” may be A only, B only, C only, A and B, A and C, B and C, or A and B and C, where any such combinations may contain one or more member or members of A, B, or C. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. The words “module,” “mechanism,” “element,” “device,” and the like may not be a substitute for the word “means.” As such, no claim element is to be construed as a means plus function unless the element is expressly recited using the phrase “means for.”

Implementation examples are described in the following numbered clauses. The following examples are illustrative only and may be combined with aspects of other embodiments or teachings described herein, without limitation.

1. A method of wireless communication at an integrated access and backhaul (IAB) apparatus, comprising: transmitting a set of values to a child IAB node, each value of the set of values corresponding to a transition type for a transition of the child IAB node between use of a mobile terminal of the child IAB node and use of a distributed unit of the child IAB node, a transition type corresponding to a first resource type for resources immediately before a transition time and to a second resource type for resources immediately after the transition time; determining that the child IAB node will perform a transition at a transition time, wherein a symbol immediately before the transition or immediately after the transition has a resource type of flexible; and providing a number of guard symbols at the transition time, the number of guard symbols being based on determining that the symbol immediately before the transition or immediately after the transition has the resource type of flexible.

2. The method of clause 1, wherein the first resource type is allocated for use by a mobile terminal of the child IAB node, and wherein the second resource type is allocated for use by a distributed unit of the child IAB node.

3. The method of clause 1, wherein the second resource type is allocated for use by a mobile terminal of the child IAB node, and wherein the first resource type is allocated for use by a distributed unit of the child IAB node.

4. The method of any of clauses 1-3, wherein: the set of values comprises a first value corresponding to a transition wherein the symbols immediately before the transition or immediately after the transition have the resource type of flexible, and the number of guard symbols is based on the first value.

5. The method of any of clauses 1-3, wherein the symbol immediately before or immediately after the transition has the resource type of flexible and is allocated to the distributed unit, and wherein the number of guard symbols is based on a value of the set of values corresponding to a transition type without a flex symbol immediately before or immediately after the transition.

6. The method of any of clauses 1-3 and 5, further comprising selecting a higher value from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the distributed unit and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the distributed unit, wherein the number of guard symbols is based on the selected value.

7. The method of any of clauses 1-3 and 5, further comprising selecting a lower value from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the distributed unit and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the distributed unit, wherein the number of guard symbols is based on the selected value.

8. The method of any of clauses 1-3, wherein the symbol immediately before or immediately after the transition has the resource type of flexible and is allocated to the mobile terminal, and wherein the number of guard symbols is based on a value of the set of values corresponding to a transition type without a flex symbol immediately before or immediately after the transition.

9. The method of any of clauses 1-3 and 8, wherein the value of the set of values is selected based on whether the symbol having the flexible type is converted to downlink or to uplink.

10. The method of any of clauses 1-3 and 8, further comprising selecting a higher value from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal, wherein the number of guard symbols is based on the selected value.

11. The method of any of clauses 1-3 and 8, further comprising selecting a lower value from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal, wherein the number of guard symbols is based on the selected value.

12. The method of any of clauses 1-11, wherein the IAB apparatus is an IAB donor or an IAB node.

13. An apparatus for communication at an IAB apparatus, comprising: means for transmitting a set of values to a child IAB node, each value of the set of values corresponding to a transition type for a transition of the child IAB node between use of a mobile terminal of the child IAB node and use of a distributed unit of the child IAB node, a transition type corresponding to a first resource type for resources immediately before a transition time and to a second resource type for resources immediately after the transition time; means for determining that the child IAB node will perform a transition at a transition time, wherein a symbol immediately before the transition or immediately after the transition has a resource type of flexible; and means for providing a number of guard symbols at the transition time, the number of guard symbols being based on determining that the symbol immediately before the transition or immediately after the transition has the resource type of flexible.

14. The apparatus of clause 13, further comprising means for performing the method of any of clauses 2-12.

15. An apparatus for wireless communication at an integrated access and backhaul (IAB) apparatus, comprising: a memory; and at least one processor coupled to the memory and configured to: transmit a set of values to a child IAB node, each value of the set of values corresponding to a transition type for a transition of the child IAB node between use of a mobile terminal of the child IAB node and use of a distributed unit of the child IAB node, a transition type corresponding to a first resource type for resources immediately before a transition time and to a second resource type for resources immediately after the transition time; determine that the child IAB node will perform a transition at a transition time, wherein a symbol immediately before the transition or immediately after the transition has a resource type of flexible; and provide a number of guard symbols at the transition time, the number of guard symbols being based on determining that the symbol immediately before the transition or immediately after the transition has the resource type of flexible.

16. The apparatus of clause 15, wherein the first resource type is allocated for use by a mobile terminal of the child IAB node, and wherein the second resource type is allocated for use by a distributed unit of the child IAB node.

17. The apparatus of clause 15, wherein the second resource type is allocated for use by a mobile terminal of the child IAB node, and wherein the first resource type is allocated for use by a distributed unit of the child IAB node.

18. The apparatus of any of clauses 15-17, wherein: the set of values comprises a first value corresponding to a transition wherein the symbols immediately before the transition or immediately after the transition have the resource type of flexible, and the number of guard symbols is based on the first value.

19. The apparatus of any of clauses 15-17, wherein the symbol immediately before or immediately after the transition has the resource type of flexible and is allocated to the distributed unit, and wherein the number of guard symbols is based on a value of the set of values corresponding to a transition type without a flex symbol immediately before or immediately after the transition.

20. The apparatus of any of clauses 15-17 and 19, wherein the processor is further configured to select a higher value from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the distributed unit and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the distributed unit, wherein the number of guard symbols is based on the selected value.

21. The apparatus of any of clauses 15-17 and 19, wherein the processor is further configured to select a lower value from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the distributed unit and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the distributed unit, wherein the number of guard symbols is based on the selected value.

22. The apparatus of any of clauses 15-17, wherein the symbol immediately before or immediately after the transition has the resource type of flexible and is allocated to the mobile terminal, and wherein the number of guard symbols is based on a value of the set of values corresponding to a transition type without a flex symbol immediately before or immediately after the transition.

23. The apparatus of any of clauses 15-17 and 22, wherein the value of the set of values is selected based on whether the symbol having the flexible type is converted to downlink or to uplink.

24. The apparatus of any of clauses 15-17 and 22, wherein the processor is further configured to select a higher value from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal, wherein the number of guard symbols is based on the selected value.

25. The apparatus of any of clauses 15-17 and 22, wherein the processor is further configured to select a lower value from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal, wherein the number of guard symbols is based on the selected value.

26. The apparatus of any of clauses 15-25, wherein the IAB apparatus is an IAB donor or an IAB node.

27. A non-transitory computer-readable medium storing computer executable code for wireless communication at a user equipment, the code when executed by a processor cause the processor to perform the method of any of clauses 1-12.

28. A method of wireless communication at an integrated access and backhaul (IAB) node, comprising: receiving a set of values from a parent IAB apparatus, each value of the set of values corresponding to a transition type for a transition of the IAB node between use of a mobile terminal of the IAB node and use of a distributed unit of the IAB node, a transition type corresponding to a first resource type for resources immediately before a transition time and to a second resource type for resources immediately after the transition time; determining to perform a transition at a transition time, wherein a symbol immediately before the transition or immediately after the transition has a resource type of flexible; and receiving a number of guard symbols at the transition time, the number of guard symbols being based on determining that the symbol immediately before the transition or immediately after the transition has the resource type of flexible.

29. The method of clause 28, wherein the first resource type is allocated for use by a mobile terminal of the IAB node, and wherein the second resource type is allocated for use by a distributed unit of the IAB node.

30. The method of clause 28, wherein the second resource type is allocated for use by a mobile terminal of the IAB node, and wherein the first resource type is allocated for use by a distributed unit of the IAB node.

31. The method of any of clauses 28-30, wherein: the set of values comprises a first value corresponding to a transition wherein the symbols immediately before the transition or immediately after the transition have the resource type of flexible, and the number of guard symbols is based on the first value.

32. The method of any of clauses 28-30, wherein the symbol immediately before or immediately after the transition has the resource type of flexible and is allocated to the distributed unit, and wherein the number of guard symbols is based on a value of the set of values corresponding to a transition type without a flex symbol immediately before or immediately after the transition.

33. The method of any of clauses 28-30 and 32, wherein the number of guard symbols is based on a higher value selected from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the distributed unit and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the distributed unit.

34. The method of any of clauses 28-30 and 32, wherein the number of guard symbols is based on a lower value selected from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the distributed unit and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the distributed unit.

35. The method of any of clauses 28-30, wherein the symbol immediately before or immediately after the transition has the resource type of flexible and is allocated to the mobile terminal, and wherein the number of guard symbols is based on a value of the set of values corresponding to a transition type without a flex symbol immediately before or immediately after the transition.

36. The method of any of clauses 28-30 and 35, wherein the value of the set of values is selected based on whether the symbol having the flexible type is converted to downlink or to uplink.

37. The method of any of clauses 28-30 and 35, wherein the number of guard symbols is based on a higher value selected from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal.

38. The method of any of clauses 28-30 and 35, wherein the number of guard symbols is based on a lower value selected from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal.

39. The method of any of clauses 28-38, wherein the IAB apparatus is a parent IAB apparatus and is an IAB donor or an IAB node.

40. An apparatus for communication at an IAB node, comprising: means for receiving a set of values from a parent IAB apparatus, each value of the set of values corresponding to a transition type for a transition of the IAB node between use of a mobile terminal of the IAB node and use of a distributed unit of the IAB node, a transition type corresponding to a first resource type for resources immediately before a transition time and to a second resource type for resources immediately after the transition time; means for determining to perform a transition at a transition time, wherein a symbol immediately before the transition or immediately after the transition has a resource type of flexible; and means for receiving a number of guard symbols at the transition time, the number of guard symbols being based on determining that the symbol immediately before the transition or immediately after the transition has the resource type of flexible.

41. The apparatus of clause 40, further comprising means for performing the method of any of clauses 29-39.

42. An apparatus for wireless communication at an integrated access and backhaul (IAB) node, comprising: a memory; and at least one processor coupled to the memory and configured to: receive a set of values from a parent IAB apparatus, each value of the set of values corresponding to a transition type for a transition of the IAB node between use of a mobile terminal of the IAB node and use of a distributed unit of the IAB node, a transition type corresponding to a first resource type for resources immediately before a transition time and to a second resource type for resources immediately after the transition time; determine to perform a transition at a transition time, wherein a symbol immediately before the transition or immediately after the transition has a resource type of flexible; and receive a number of guard symbols at the transition time, the number of guard symbols being based on determining that the symbol immediately before the transition or immediately after the transition has the resource type of flexible.

43. The apparatus of clause 42, wherein the first resource type is allocated for use by a mobile terminal of the IAB node, and wherein the second resource type is allocated for use by a distributed unit of the IAB node.

44. The apparatus of clause 42, wherein the second resource type is allocated for use by a mobile terminal of the IAB node, and wherein the first resource type is allocated for use by a distributed unit of the IAB node.

45. The apparatus of any of clauses 42-44, wherein: the set of values comprises a first value corresponding to a transition wherein the symbols immediately before the transition or immediately after the transition have the resource type of flexible, and the number of guard symbols is based on the first value.

46. The apparatus of any of clauses 42-44, wherein the symbol immediately before or immediately after the transition has the resource type of flexible and is allocated to the distributed unit, and wherein the number of guard symbols is based on a value of the set of values corresponding to a transition type without a flex symbol immediately before or immediately after the transition.

47. The apparatus of any of clauses 42-44 and 46, wherein the number of guard symbols is based on a higher value selected from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the distributed unit and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the distributed unit.

48. The apparatus of any of clauses 42-44 and 46, wherein the number of guard symbols is based on a lower value selected from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the distributed unit and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the distributed unit.

49. The apparatus of any of clauses 42-44, wherein the symbol immediately before or immediately after the transition has the resource type of flexible and is allocated to the mobile terminal, and wherein the number of guard symbols is based on a value of the set of values corresponding to a transition type without a flex symbol immediately before or immediately after the transition.

50. The apparatus of any of clauses 42-44 and 49, wherein the value of the set of values is selected based on whether the symbol having the flexible type is converted to downlink or to uplink.

51. The apparatus of any of clauses 42-44 and 49, wherein the number of guard symbols is based on a higher value selected from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal.

52. The apparatus of any of clauses 42-44 and 49, wherein the number of guard symbols is based on a lower value selected from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal.

53. The apparatus of any of clauses 42-52, wherein the IAB apparatus is a parent IAB apparatus and is an IAB donor or an IAB node.

54. A non-transitory computer-readable medium storing computer executable code for wireless communication at a user equipment, the code when executed by a processor cause the processor to perform the method of any of clauses 28-39.

55. A method of wireless communication at an integrated access and backhaul (IAB) node, comprising: transmitting a set of values to a parent IAB apparatus, each value of the set of values corresponding to a transition type for a transition of the IAB node between use of a mobile terminal of the IAB node and use of a distributed unit of the IAB node, a transition type corresponding to a first resource type for resources immediately before a transition time and to a second resource type for resources immediately after the transition time; determining to perform a transition at a transition time, wherein a symbol immediately before the transition or immediately after the transition has a resource type of flexible; and receiving a number of guard symbols from the parent IAB apparatus at the transition time, the number of guard symbols being based on determining that the symbol immediately before the transition or immediately after the transition has the resource type of flexible.

56. The method of clause 55, wherein the first resource type is allocated for use by a mobile terminal of the IAB node, and wherein the second resource type is allocated for use by a distributed unit of the IAB node.

57. The method of clause 55, wherein the second resource type is allocated for use by a mobile terminal of the IAB node, and wherein the first resource type is allocated for use by a distributed unit of the IAB node.

58. The method of any of clauses 55-57, wherein: the set of values comprises a first value corresponding to a transition wherein the symbols immediately before the transition or immediately after the transition have the resource type of flexible, and the number of guard symbols is based on the first value.

59. The method of any of clauses 55-57, wherein the symbol immediately before or immediately after the transition has the resource type of flexible and is allocated to the distributed unit, and wherein the number of guard symbols is based on a value of the set of values corresponding to a transition type without a flex symbol immediately before or immediately after the transition.

60. The method of any of clauses 55-57 and 59, wherein the number of guard symbols is based on a higher value selected from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the distributed unit and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the distributed unit.

61. The method of any of clauses 55-57 and 59, wherein the number of guard symbols is based on a lower value selected from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the distributed unit and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the distributed unit.

62. The method of any of clauses 55-57, wherein the symbol immediately before or immediately after the transition has the resource type of flexible and is allocated to the mobile terminal, and wherein the number of guard symbols is based on a value of the set of values corresponding to a transition type without a flex symbol immediately before or immediately after the transition.

63. The method of any of clauses 55-57 and 62, wherein the value of the set of values is selected based on whether the symbol having the flexible type is converted to downlink or to uplink.

64. The method of any of clauses 55-57 and 62, wherein the number of guard symbols is based on a higher value selected from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal.

65. The method of any of clauses 55-57 and 62, wherein the number of guard symbols is based on a lower value selected from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal.

66. The method of any of clauses 55-65, wherein the parent IAB apparatus is an IAB donor or an IAB node.

67. An apparatus for communication at an IAB node, comprising: means for transmitting a set of values to a parent IAB apparatus, each value of the set of values corresponding to a transition type for a transition of the IAB node between use of a mobile terminal of the IAB node and use of a distributed unit of the IAB node, a transition type corresponding to a first resource type for resources immediately before a transition time and to a second resource type for resources immediately after the transition time; means for determining to perform a transition at a transition time, wherein a symbol immediately before the transition or immediately after the transition has a resource type of flexible; and means for receiving a number of guard symbols from the parent IAB apparatus at the transition time, the number of guard symbols being based on determining that the symbol immediately before the transition or immediately after the transition has the resource type of flexible.

68. The apparatus of clause 67, further comprising means for performing the method of any of clauses 56-66.

69. An apparatus for wireless communication at an integrated access and backhaul (IAB) node, comprising: a memory; and at least one processor coupled to the memory and configured to: transmit a set of values to a parent IAB apparatus, each value of the set of values corresponding to a transition type for a transition of the IAB node between use of a mobile terminal of the IAB node and use of a distributed unit of the IAB node, a transition type corresponding to a first resource type for resources immediately before a transition time and to a second resource type for resources immediately after the transition time; determine to perform a transition at a transition time, wherein a symbol immediately before the transition or immediately after the transition has a resource type of flexible; and receive a number of guard symbols from the parent IAB apparatus at the transition time, the number of guard symbols being based on determining that the symbol immediately before the transition or immediately after the transition has the resource type of flexible.

70. The apparatus of clause 69, wherein the first resource type is allocated for use by a mobile terminal of the IAB node, and wherein the second resource type is allocated for use by a distributed unit of the IAB node.

71. The apparatus of clause 69, wherein the second resource type is allocated for use by a mobile terminal of the IAB node, and wherein the first resource type is allocated for use by a distributed unit of the IAB node.

72. The apparatus of any of clauses 69-71, wherein: the set of values comprises a first value corresponding to a transition wherein the symbols immediately before the transition or immediately after the transition have the resource type of flexible, and the number of guard symbols is based on the first value.

73. The apparatus of any of clauses 69-71, wherein the symbol immediately before or immediately after the transition has the resource type of flexible and is allocated to the distributed unit, and wherein the number of guard symbols is based on a value of the set of values corresponding to a transition type without a flex symbol immediately before or immediately after the transition.

74. The apparatus of any of clauses 69-71 and 73, wherein the number of guard symbols is based on a higher value selected from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the distributed unit and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the distributed unit.

75. The apparatus of any of clauses 69-71 and 73, wherein the number of guard symbols is based on a lower value selected from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the distributed unit and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the distributed unit.

76. The apparatus of any of clauses 69-71, wherein the symbol immediately before or immediately after the transition has the resource type of flexible and is allocated to the mobile terminal, and wherein the number of guard symbols is based on a value of the set of values corresponding to a transition type without a flex symbol immediately before or immediately after the transition.

77. The apparatus of any of clauses 69-71 and 76, wherein the value of the set of values is selected based on whether the symbol having the flexible type is converted to downlink or to uplink.

78. The apparatus of any of clauses 69-71 and 76, wherein the number of guard symbols is based on a higher value selected from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal.

79. The apparatus of any of clauses 69-71 and 76, wherein the number of guard symbols is based on a lower value selected from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal.

80. The apparatus of any of clauses 69-79, wherein the parent IAB apparatus is an IAB donor or an IAB node.

81. A non-transitory computer-readable medium storing computer executable code for wireless communication at a user equipment, the code when executed by a processor cause the processor to perform the method of any of clauses 55-66.

82. A method of wireless communication at an integrated access and backhaul (IAB) apparatus, comprising: receiving a set of values from a child IAB node, each value of the set of values corresponding to a transition type for a transition of the child IAB node between use of a mobile terminal of the child IAB node and use of a distributed unit of the child IAB node, a transition type corresponding to a first resource type for resources immediately before a transition time and to a second resource type for resources immediately after the transition time; determining that the child IAB node will perform a transition at a transition time, wherein a symbol immediately before the transition or immediately after the transition has a resource type of flexible; and providing a number of guard symbols at the transition time, the number of guard symbols being based on determining that the symbol immediately before the transition or immediately after the transition has the resource type of flexible.

83. The method of clause 82, wherein the first resource type is allocated for use by a mobile terminal of the child IAB node, and wherein the second resource type is allocated for use by a distributed unit of the child IAB node.

84. The method of clause 82, wherein the second resource type is allocated for use by a mobile terminal of the child IAB node, and wherein the first resource type is allocated for use by a distributed unit of the child IAB node.

85. The method of any of clauses 82-84, wherein: the set of values comprises a first value corresponding to a transition wherein the symbols immediately before the transition or immediately after the transition have the resource type of flexible, and the number of guard symbols is based on the first value.

86. The method of any of clauses 82-84, wherein the symbol immediately before or immediately after the transition has the resource type of flexible and is allocated to the distributed unit, and wherein the number of guard symbols is based on a value of the set of values corresponding to a transition type without a flex symbol immediately before or immediately after the transition.

87. The method of any of clauses 82-84 and 86, further comprising selecting a higher value from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the distributed unit and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the distributed unit, wherein the number of guard symbols is based on the selected value.

88. The method of any of clauses 82-84 and 86, further comprising selecting a lower value from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the distributed unit and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the distributed unit, wherein the number of guard symbols is based on the selected value.

89. The method of any of clauses 82-84, wherein the symbol immediately before or immediately after the transition has the resource type of flexible and is allocated to the mobile terminal, and wherein the number of guard symbols is based on a value of the set of values corresponding to a transition type without a flex symbol immediately before or immediately after the transition.

90. The method of any of clauses 82-84 and 89, wherein the value of the set of values is selected based on whether the symbol having the flexible type is converted to downlink or to uplink.

91. The method of any of clauses 82-84 and 89, further comprising selecting a higher value from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal, wherein the number of guard symbols is based on the selected value.

92. The method of any of clauses 82-84 and 89, further comprising selecting a lower value from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal, wherein the number of guard symbols is based on the selected value.

93. The method of any of clauses 82-92, wherein the IAB apparatus is an IAB donor or an IAB node.

94. An apparatus for communication at an IAB apparatus, comprising: means for receiving a set of values from a child IAB node, each value of the set of values corresponding to a transition type for a transition of the child IAB node between use of a mobile terminal of the child IAB node and use of a distributed unit of the child IAB node, a transition type corresponding to a first resource type for resources immediately before a transition time and to a second resource type for resources immediately after the transition time; means for determining that the child IAB node will perform a transition at a transition time, wherein a symbol immediately before the transition or immediately after the transition has a resource type of flexible; and means for providing a number of guard symbols at the transition time, the number of guard symbols being based on determining that the symbol immediately before the transition or immediately after the transition has the resource type of flexible.

95. The apparatus of clause 94, further comprising means for performing the method of any of clauses 83-93.

96. An apparatus for wireless communication at an integrated access and backhaul (IAB) apparatus, comprising: a memory; and at least one processor coupled to the memory and configured to: receive a set of values from a child IAB node, each value of the set of values corresponding to a transition type for a transition of the child IAB node between use of a mobile terminal of the child IAB node and use of a distributed unit of the child IAB node, a transition type corresponding to a first resource type for resources immediately before a transition time and to a second resource type for resources immediately after the transition time; determine that the child IAB node will perform a transition at a transition time, wherein a symbol immediately before the transition or immediately after the transition has a resource type of flexible; and provide a number of guard symbols at the transition time, the number of guard symbols being based on determining that the symbol immediately before the transition or immediately after the transition has the resource type of flexible.

97. The apparatus of clause 96, wherein the first resource type is allocated for use by a mobile terminal of the child IAB node, and wherein the second resource type is allocated for use by a distributed unit of the child IAB node.

98. The apparatus of clause 96, wherein the second resource type is allocated for use by a mobile terminal of the child IAB node, and wherein the first resource type is allocated for use by a distributed unit of the child IAB node.

99. The apparatus of any of clauses 96-98, wherein: the set of values comprises a first value corresponding to a transition wherein the symbols immediately before the transition or immediately after the transition have the resource type of flexible, and the number of guard symbols is based on the first value.

100. The apparatus of any of clauses 96-98, wherein the symbol immediately before or immediately after the transition has the resource type of flexible and is allocated to the distributed unit, and wherein the number of guard symbols is based on a value of the set of values corresponding to a transition type without a flex symbol immediately before or immediately after the transition.

101. The apparatus of any of clauses 96-98 and 100, further comprising selecting a higher value from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the distributed unit and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the distributed unit, wherein the number of guard symbols is based on the selected value.

102. The apparatus of any of clauses 96-98 and 100, further comprising selecting a lower value from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the distributed unit and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the distributed unit, wherein the number of guard symbols is based on the selected value.

103. The apparatus of any of clauses 96-98, wherein the symbol immediately before or immediately after the transition has the resource type of flexible and is allocated to the mobile terminal, and wherein the number of guard symbols is based on a value of the set of values corresponding to a transition type without a flex symbol immediately before or immediately after the transition.

104. The apparatus of any of clauses 96-98 and 103, wherein the value of the set of values is selected based on whether the symbol having the flexible type is converted to downlink or to uplink.

105. The apparatus of any of clauses 96-98 and 103, further comprising selecting a higher value from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal, wherein the number of guard symbols is based on the selected value.

106. The apparatus of any of clauses 96-98 and 103, further comprising selecting a lower value from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal, wherein the number of guard symbols is based on the selected value.

107. The apparatus of any of clauses 96-106, wherein the IAB apparatus is an IAB donor or an IAB node.

108. A non-transitory computer-readable medium storing computer executable code for wireless communication at a user equipment, the code when executed by a processor cause the processor to perform the method of any of clauses 82-93. 

What is claimed is:
 1. A method of wireless communication at an integrated access and backhaul (IAB) apparatus, comprising: transmitting a set of values to a child IAB node or receiving the set of values from the child IAB node, each value of the set of values corresponding to a transition type for a transition of the child IAB node between use of a mobile terminal of the child IAB node and use of a distributed unit of the child IAB node, a transition type corresponding to a first resource type for resources immediately before a transition time and to a second resource type for resources immediately after the transition time; determining that the child IAB node will perform the transition at the transition time, wherein a symbol immediately before the transition or immediately after the transition has a resource type of flexible; and providing a number of guard symbols at the transition time, the number of guard symbols being based on determining that the symbol immediately before the transition or immediately after the transition has the resource type of flexible.
 2. The method of claim 1, wherein: the set of values comprises a first value corresponding to a transition wherein the symbols immediately before the transition or immediately after the transition have the resource type of flexible, and the number of guard symbols is based on the first value.
 3. The method of claim 1, wherein the symbol immediately before or immediately after the transition has the resource type of flexible and is allocated to the distributed unit, and wherein the number of guard symbols is based on a value of the set of values corresponding to a transition type without a flex symbol immediately before or immediately after the transition.
 4. The method of claim 3, further comprising selecting a lower value or selecting a higher value from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the distributed unit and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the distributed unit, wherein the number of guard symbols is based on the selected value.
 5. The method of claim 1, wherein the symbol immediately before or immediately after the transition has the resource type of flexible and is allocated to the mobile terminal, and wherein the number of guard symbols is based on a value of the set of values corresponding to a transition type without a flex symbol immediately before or immediately after the transition.
 6. The method of claim 5, wherein the value of the set of values is selected based on whether the symbol having the flexible type is converted to downlink or to uplink.
 7. The method of claim 5, further comprising selecting a lower value or selecting a higher value from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal, wherein the number of guard symbols is based on the selected value.
 8. A method of wireless communication at an integrated access and backhaul (IAB) node, comprising: receiving a set of values from a parent IAB apparatus or transmitting the set of values to the parent IAB apparatus, each value of the set of values corresponding to a transition type for a transition of the IAB node between use of a mobile terminal of the IAB node and use of a distributed unit of the IAB node, a transition type corresponding to a first resource type for resources immediately before a transition time and to a second resource type for resources immediately after the transition time; determining to perform the transition at the transition time, wherein a symbol immediately before the transition or immediately after the transition has a resource type of flexible; and receiving a number of guard symbols at the transition time, the number of guard symbols being based on determining that the symbol immediately before the transition or immediately after the transition has the resource type of flexible.
 9. The method of claim 8, wherein: the set of values comprises a first value corresponding to a transition wherein the symbols immediately before the transition or immediately after the transition have the resource type of flexible, and the number of guard symbols is based on the first value.
 10. The method of claim 8, wherein the symbol immediately before or immediately after the transition has the resource type of flexible and is allocated to the distributed unit, and wherein the number of guard symbols is based on a value of the set of values corresponding to a transition type without a flex symbol immediately before or immediately after the transition.
 11. The method of claim 10, wherein the number of guard symbols is based on a lower value or is based on a higher value selected from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the distributed unit and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the distributed unit.
 12. The method of claim 8, wherein the symbol immediately before or immediately after the transition has the resource type of flexible and is allocated to the mobile terminal, and wherein the number of guard symbols is based on a value of the set of values corresponding to a transition type without a flex symbol immediately before or immediately after the transition.
 13. The method of claim 12, wherein the value of the set of values is selected based on whether the symbol having the flexible type is converted to downlink or to uplink.
 14. The method of claim 12, wherein the number of guard symbols is based on a lower value or is based on a higher value selected from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal.
 15. An apparatus for wireless communication at an integrated access and backhaul (IAB) apparatus, comprising: a memory; and at least one processor coupled to the memory and configured to: transmit a set of values to a child IAB node or receiving the set of values from the child IAB node, each value of the set of values corresponding to a transition type for a transition of the child IAB node between use of a mobile terminal of the child IAB node and use of a distributed unit of the child IAB node, a transition type corresponding to a first resource type for resources immediately before a transition time and to a second resource type for resources immediately after the transition time; determine that the child IAB node will perform the transition at the transition time, wherein a symbol immediately before the transition or immediately after the transition has a resource type of flexible; and provide a number of guard symbols at the transition time, the number of guard symbols being based on determining that the symbol immediately before the transition or immediately after the transition has the resource type of flexible.
 16. The apparatus of claim 15, wherein: the set of values comprises a first value corresponding to a transition wherein the symbols immediately before the transition or immediately after the transition have the resource type of flexible, and the number of guard symbols is based on the first value.
 17. The apparatus of claim 15, wherein the symbol immediately before or immediately after the transition has the resource type of flexible and is allocated to the distributed unit, and wherein the number of guard symbols is based on a value of the set of values corresponding to a transition type without a flex symbol immediately before or immediately after the transition.
 18. The apparatus of claim 17, wherein the at least one processor is further configured to select a lower value or select a higher value from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the distributed unit and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the distributed unit, wherein the number of guard symbols is based on the selected value.
 19. The apparatus of claim 15, wherein the symbol immediately before or immediately after the transition has the resource type of flexible and is allocated to the mobile terminal, and wherein the number of guard symbols is based on a value of the set of values corresponding to a transition type without a flex symbol immediately before or immediately after the transition.
 20. The apparatus of claim 19, wherein the value of the set of values is selected based on whether the symbol having the flexible type is converted to downlink or to uplink.
 21. The apparatus of claim 19, wherein the at least one processor is further configured to select a lower value or select a higher value from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal, wherein the number of guard symbols is based on the selected value.
 22. The apparatus of claim 15, wherein the IAB apparatus is an IAB donor or an IAB node.
 23. An apparatus for of wireless communication at an integrated access and backhaul (IAB) node, comprising: a memory; and at least one processor coupled to the memory and configured to: receive a set of values from a parent IAB apparatus or transmitting the set of values to the parent IAB apparatus, each value of the set of values corresponding to a transition type for a transition of the IAB node between use of a mobile terminal of the IAB node and use of a distributed unit of the IAB node, a transition type corresponding to a first resource type for resources immediately before a transition time and to a second resource type for resources immediately after the transition time; determine to perform the transition at the transition time, wherein a symbol immediately before the transition or immediately after the transition has a resource type of flexible; and receive a number of guard symbols at the transition time, the number of guard symbols being based on determining that the symbol immediately before the transition or immediately after the transition has the resource type of flexible.
 24. The apparatus of claim 23, wherein: the set of values comprises a first value corresponding to a transition wherein the symbols immediately before the transition or immediately after the transition have the resource type of flexible, and the number of guard symbols is based on the first value.
 25. The apparatus of claim 23, wherein the symbol immediately before or immediately after the transition has the resource type of flexible and is allocated to the distributed unit, and wherein the number of guard symbols is based on a value of the set of values corresponding to a transition type without a flex symbol immediately before or immediately after the transition.
 26. The apparatus of claim 25, wherein the number of guard symbols is based on a lower value or is based on a higher value selected from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the distributed unit and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the distributed unit.
 27. The apparatus of claim 23, wherein the symbol immediately before or immediately after the transition has the resource type of flexible and is allocated to the mobile terminal, and wherein the number of guard symbols is based on a value of the set of values corresponding to a transition type without a flex symbol immediately before or immediately after the transition.
 28. The apparatus of claim 27, wherein the value of the set of values is selected based on whether the symbol having the flexible type is converted to downlink or to uplink.
 29. The apparatus of claim 27, wherein the number of guard symbols is based on a lower value or is based on a higher value selected from a first value of the set of values corresponding to a transition type having a downlink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal and a second value of the set of values corresponding to a transition type having an uplink type for the symbol immediately before or immediately after the transition allocated to the mobile terminal.
 30. The apparatus of claim 23, wherein the parent IAB apparatus is an IAB donor or an IAB node. 